Where there is a will, there is a way. The Western world also abolished slavery despite World wars 1 and 2. But Islam not only didn't abolish slavery, but it even usurped many human rights, which could be very easily given to slaves.

Muslim preachers come up with this excuse:

Look how the black African American slaves, after being set free by the 13th Amendment, suffered and some of them died after being freed. Thus Islam couldn't abolish slavery because then the slaves would suffer the same fate as the black American slaves.

Simlialry, every war brought slaves, and Muslims could not have abolished it one-sidedly, when Kuffars were also enslaving Muslims after wars. 

Moreover, the economy was directly linked with slavery, and it was impossible to completely abolish slavery, and to give freedom to all slaves who were the private properties of their owners, who bought them from slave markets. 

Response:

Firstly, the Muslim argument about African American slaves holds no value. Slavery was also abolished in the whole of Europe, but no such problem occurred in Europe. Actually, The British Empire also abolished slavery from all its colonies all over the world, and still, slaves faced no such problems in those colonies. 

Actually, it was the "Racial Prejudice" of the white supremacists in America, which played the most important role in bringing hardships to African American Slaves later after their emancipation. The question is if Sahaba (i.e. companions of Muhammad) also had such "Racial Prejudice" against all slaves that Allah/Muhammad feared and thus didn't dare to emancipate slaves in the Islamic state.

Secondly and most importantly, if ongoing wars were bringing more slaves every time, still Allah/Muhammad could have given slaves more human rights, which could have reduced their sufferings. But Allah/Muhammad failed miserably in providing the slaves with even basic human rights

For example, Ashoka the Great of India was also not able to completely eradicate slavery due to ongoing wars. However, he successfully eliminated all forms of slave trade and slave markets within India.

Here is a list of some basic human rights, which Allah/Muhammad could have very easily provided to slaves, and his companions would have not rebelled against Allah/Muhammad. The economy of the Islamic State would have also not collapsed due to those basic human rights:

  1. Allah/Muhammad could have at least ordered if anyone desired the captive woman, then he should marry her, and should not further sell her to another man after a temporary sexual relationship. If the Bible successfully gave this right to the poor captive and slave women thousands of years before Islam, what then stopped Allah/Muhammad from giving this important basic human right to the captive/slave women? Instead of that, Allah/Muhammad made the repetitive rape and repetitive sale of slave women Halal in the name of temporary sexual relationships. [More details here]

  2. Allah/Muhammad could have at least abolished the rape of the virgin and small girls on the first night. If the Jews and the Christians (who were the neighbours of Muhammad) were following the rule of the Bible and not raping captive women and girls for the first full month for thousands of years before Muhammad, why then was it impossible for Allah/Muhammad to do the same? [More details here]

  3. Had Prophet Muhammad wished, then he could have allowed the slave women to take Hijab (when they were not working) and to cover their naked breasts. It has nothing to do with economic conditions but with basic human rights. But Allah/Muhammad went towards the opposite direction. Not only breasts of slave women were kept naked, but they were also beaten with sticks if they ever wished to cover their bodies by wearing a Hijab. [More details here]

  4. Allah/Muhammad could have accepted the testimony of slaves in the court, and Sahaba would not have revolted against Allah/Muhammad for that, while it has nothing to do with the economic situation. But Allah/Muhammad wanted to dishonour the slave men and women. In fact, Islam/Muhammad didn't even allow the non-Muslims to give testimony against any crime of any free Muslim man in the court. It was also in order to humiliate the non-Muslims. While Allah/Muhammad usurped the right of "witness" from slave women, thus those poor women were not even able to go to the courts and give witness against the rapist who raped them, or against their own owners if they forced them into prostitution. That is why verse 33:59 tells that Sahaba used to sit on the roads and used to sexually molest the slave women. And Allah/Muhammad didn't punish those companions but only differentiated the free women from the slave through the use of the Hijab so that Sahaba didn't then molest the free women. [More details here]

  5. Allah/Muhammad could have easily spared the old elderly men by not killing them after taking them as prisoners. Did sparing the elderly men would have destroyed the economy of the mighty Islamic Caliphate?  [More details here]

  6. Allah/Muhammad could have easily declared that the life of a slave had equal value as that of his owner. And he could have easily imposed Qisas (or any other kind of physical punishment) in order to discourage the owners to beat or to kill their slaves. Merely giving a recommendation not to slap them was not enough, and there should have been any physical punishment for the owners for beating or killing them. Again, this has nothing to do with the economic situation, but basic human rights. Had Sahaba revolted against Allah/Muhammad if they had declared the blood of slaves equal to their owners? [More details here

  7. He could have allowed the slaves to indulge in love, and to marry the woman of their choice. Would giving such basic human rights to the slaves have really destroyed the Economy of the mighty Islamic State? [More details here

  8. He could have prohibited the Muslim masters from destroying the slave family by taking the wife of his male slave for his lust and raping her. [More details here

  9. He could have ordered that owners were not allowed to disown the parentage of their own children from their slave women. How much did it affect the Economy of the Islamic State? [More details here

  10. He could have ordered to end of the institution of “Slavery by Birth” (i.e. children of slaves are automatically born as slaves in Islam). Did that really destroy the Economy of the mighty Islamic State? [More details here

  11. He could have ordered that it was not allowed to separate the babies (after they got two molar teeth at the age of 6 months) from their slave mothers and then sell them in the Islamic Bazaars of Slavery. Did the prohibition of such sale of 6-month-old babies really destroy the economy of the mighty Islamic State? [More details here

  12. If any slave fled away, then it means he wanted to live as a free man. But Muhammad ordered the slaughter of the slave if he fled. Why? [More details here]

  13. He could have prohibited the “private ownership” of the slaves and could have declared that all the captives/slaves should only be kept in the ownership of the State. For example, the Law of Draco (which was written 1200 years before Islam), declared that only the State had the right to own the slaves (link).

  14. He could have at least ended the Bazaars of Slavery, where poor slave women were paraded half-naked, and the buyers were even allowed to touch their private body parts too. If Ashoka the Great of India could have ended the Slave Trade and the Bazaars of Slavery 800 years before Islam, why then Muhammad (or powerful Muslim rulers like Umar Ibn Khattab) were unable to end the slave trade and the Bazaars of Slavery? [More details here]

  15. He could have at least ended the slave trade with the non-Muslim countries, where the Muslim owners were even able to sell the Muslim/Jews/Christian slave women to the Polytheists, who raped those women, although those slave women believed in God (Reference: History of Tabari, vol. 8, Page 39 under the incident of Banu Qurayzah). After that Prophet Muhammad handed over the captive (Jewish) women to companion Saad bin Zayd, and sent him to the area of Najd, so that he could sell those captive (Jew) women there (to the polytheists) and buy weapons and horses from that money.

  16. Muslim Bazaars of Slavery were notoriously famous throughout the world and became one of the major sources of income for the Muslim community. But such an economic source from slavery is even worse than the economic sources from other crimes like stealing and robbery. 

  17. He could have replaced the institution of slavery with the institution of Serfdom (like the Buddhist Governments of the 13th century did for the sake of humanity, and to give basic human rights to the slaves (Link). If the normal Buddhist States were able to do it, why then Muhammad or later coming powerful Muslim rulers not able to do it?

As the wise people say: “Where there is a will, there is a way”. But Allah/Muhammad was unable to find ways to end slavery, or even to give basic human rights to the slaves, while they didn’t will it. Otherwise, Muhammad and other powerful Muslim rulers got all the full power and economic stability to abolish slavery completely.

In conclusion, even if Muhammad/Allah was not able to abolish slavery completely, still he was in the position of providing the slaves with these basic human rights, thus reducing their sufferings. But Muhammad/Allah failed miserably here.

And in many cases, Muhammad/Allah even INCREASED the sufferings of slaves (like raping captive/slave women in Temporary sexual relationships Halal for Mulsim men and then selling them to another master). While Muhammad's neighbours (i.e. the Jews and Christians) were neither allowing the practice of temporary sexual relationships with captive/slave girls, nor they were allowing multiple masters to rape their shared slave girl, nor they were allowing the swapping of slave girls, nor they were allowing the masters to take the wife of their male slaves for their lust. 

Islamists' Excuse: The West abolished slavery only due to the "Industrial Revolution"

All Islamic apologists (link) today come up with another excuse that the West abolished slavery only due to the Industrial Revolution, as they didn't need slave labour after the development of steam engine.

However, this claim is not right. There was already a long historical movement present against slavery in the West before any industrial revolution. This movement was solely based upon HUMANITY and had nothing to do with the industrial revolution.

Here is the timeline of Abolishment of Slavery:

https://en.wikipedia.org/wiki/Timeline_of_abolition_of_slavery_and_serfdom

Medieval times

[edit]
N.B.: Many of the listed reforms were reversed over succeeding centuries.
Date Jurisdiction Description
590–604  Rome Pope Gregory I bans Jews from owning Christian slaves.[8]
7th century Francia Queen Balthild, a former slave, and the Council of Chalon-sur-Saône (644–655) condemn the enslavement of Christians. Balthild purchases slaves, mostly Saxon, and manumits (frees) them.[9]
741–752  Rome Pope Zachary bans the sale of Christian slaves to Muslims, purchases all slaves acquired in the city by Venetian slave traders, and sets them free.
840  Carolingian Empire
 Venice
Pactum Lotharii: Venice pledges to neither buy Christian slaves in the Empire, nor sell them to Muslims. Venetian slave traders switch to trading Slavs from the East (Balkan slave trade).
873 Christendom Pope John VIII declares the enslavement of fellow Christians a sin and commands their release.[10]
~900 Byzantine Empire Emperor Leo VI the Wise prohibits voluntary self-enslavement and commands that such contracts shall be null and void and punishable by flagellation for both parties to the contract.[11]
956 Goryeo Dynasty (Korea) Slaves were freed on a large scale in 956 by the Goryeo dynasty.[12] Gwangjong of Goryeo proclaimed the Slave and Land Act (노비안검법, 奴婢按檢法), an act that "deprived nobles of much of their manpower in the form of slaves and purged the old nobility, the meritorious subjects and their offspring and military lineages in great numbers".[13]
960  Venice Slave trade banned in the city under the rule of Doge Pietro IV Candiano.
1080  Norman England William the Conqueror prohibits the sale of any person to "heathens" (non-Christians) as slaves.
1100  Normandy Serfdom no longer present.[14]
1102  Norman England The Council of London bans the slave trade: "Let no one dare hereafter to engage in the infamous business, prevalent in England, of selling men like animals."[15][16]
c. 1160  Norway The Gulating bans the sale of house slaves out of the country.[citation needed]
1171  Ireland All English slaves in the island freed by the Council of Armagh.[16]
1198  France Trinitarian Order founded with the purpose of redeeming war captives.
1214 Korčula The Statute of the Town abolishes slavery.[17][18][better source needed]
1218 Catalonia Aragon Mercedarians founded in Barcelona with the purpose of ransoming poor Christians enslaved by Muslims.
~1220  Holy Roman Empire The Sachsenspiegel, the most influential German code of law from the Middle Ages, condemns slavery as a violation of man's likeness to God.[19]
1245 Catalonia Aragon James I bans Jews from owning Christian slaves, but allows them to own Muslims and Pagans.[20]
1256  Bologna Liber Paradisus promulgated. Slavery and serfdom abolished, all serfs in the commune are released.
1315  France Louis X publishes a decree abolishing slavery and proclaiming that "France signifies freedom", that any slave setting foot on French ground should be freed.[21] However some limited cases of slavery continued until the 17th century in some of France's Mediterranean harbours in Provence, as well as until the 18th century in some of France's overseas territories.[22] Most aspects of serfdom are also eliminated de facto between 1315 and 1318.[23]
1318  France King Philip V abolishes serfdom in his domain.[24]
1335  Sweden Slavery abolished (including Sweden's territory in Finland). However, slaves are not banned entry into the country until 1813.[25] Between 1784 and 1847, slavery was practiced in the Swedish-ruled Caribbean island of Saint Barthélemy. Sweden never practiced serfdom, except in a few territories it later acquired which were ruled under a local legal code.
1347  Poland The Statutes of Casimir the Great issued in Wiślica emancipate all non-free people.[26]
1368  Ming Dynasty Emperor Hongwu abolished most forms of slavery,[6] limiting even the highest ranks of household to less than 20 household slaves. Later in the dynasty saw a resurgence of debt servitude, primarily in the south, as a result of population growth against the dearth of arable lands, often taking euphemisms like "adoption" to circumvent its still outlawed status.[27]
1416  Ragusa Slavery and slave trade abolished.
1423  Poland King orders to free all Christian slaves.[28]
1435  Canary Islands Pope Eugene IV's Sicut Dudum bans enslavement of baptised Christians, "or those freely seeking baptism" in the Canary Islands on pain of excommunication.[29]
1477 Crown of Castile Castile Isabella I bans slavery in newly conquered territories.[30]
1480  Galicia Remnant serfdom abolished by the Catholic Monarchs.[31]
1486 Crown of Aragon Aragon Ferdinand II promulgates the Sentence of Guadalupe, abolishing Carolingian-remnant serfdom (remença) in Old Catalonia.
1490 Crown of Castile Castile After a long court case, the Catholic Monarchs order that all La Gomera natives enslaved in the aftermath of the 1488 rebellion must be freed and returned to the island at Conquistador Pedro de Vera's expense. De Vera is also relieved from his post as Governor of Gran Canaria in 1491.[32]
1493 Queen Isabella bans the enslavement of Native Americans unless they are hostile or cannibalistic.[30] Native Americans are ruled to be subjects of the Crown. Columbus is preempted from selling Indian captives in Seville and those already sold are tracked, purchased from their buyers and released.

    1500–170

    Date Jurisdiction Description
    1503 Crown of Castile Castile Native Americans allowed to travel to Spain only on their own free will.[33]
    1512 The Laws of Burgos establish limits to the treatment of natives in the Encomienda system.
    1518 Spanish Empire Spain Decree of Holy Roman Emperor Charles V establishing the importation of African slaves to the Americas, under monopoly of Laurent de Gouvenot, in an attempt to discourage enslavement of Native Americans.
    1528 Charles V forbids the transportation of Native Americans to Europe, even on their own will, in an effort to curtail their enslavement. Encomiendas are banned from collecting tribute in gold with the reasoning that Natives were selling their children to get it.[34]
    1530 Outright slavery of Native Americans under any circumstance is banned. However, forced labor under the Encomienda continues.
    1536 The Welser family is dispossessed of the Asiento monopoly (granted in 1528) following complaints about their treatment of Native American workers in Venezuela.
    1537 New World Pope Paul III forbids slavery of the indigenous peoples of the Americas and any other population to be discovered, establishing their right to freedom and property (Sublimis Deus).[35]
    1542 Spanish Empire Spain The New Laws ban slave raiding in the Americas and abolish the slavery of natives, but replace it with other systems of forced labor like the repartimiento. Slavery of Black Africans continues.[22] New limits are imposed to the Encomienda.
    1549 Encomiendas banned from using forced labor.
    1550-1551 Valladolid Debate on the innate rights of indigenous peoples of the Americas.
    1552 Bartolomé de las Casas, "the first to expose the oppression of indigenous peoples by Europeans in the Americas and to call for the abolition of slavery there."[36]
    1562  Mughal Empire (Secular) Akbar restricted enslavement by his soldiery.[37]
    1570  Portugal King Sebastian of Portugal bans the enslavement of Native Americans under Portuguese rule, allowing only the enslavement of hostile ones. This law was highly influenced by the Society of Jesus, which had missionaries in direct contact with Brazilian tribes.
    1574  England Last remaining serfs emancipated by Elizabeth I.[23]
     Philippines Slavery abolished by royal decree.[38]
    1588  Lithuania The Third Statute of Lithuania abolishes slavery.[39]
    1590  Japan Toyotomi Hideyoshi bans slavery except as punishment for criminals.[40]
    1595  Portugal Trade of Chinese slaves banned.[41]
    1602  England The Clifton Star Chamber Case set a precedent, that impressing / enslaving children to serve as actors was illegal.
    1609 Spanish Empire Spain The Moriscos, many of whom are serfs, are expelled from Peninsular Spain unless they become slaves voluntarily (known as moros cortados, "cut Moors") However, a large proportion avoid expulsion or manage to return.[42]
    1624  Portugal Enslavement of Chinese banned.[43][44]
    1649  Russia The sale of Russian slaves to Muslims is banned.[45]
    1652  Providence Plantations Roger Williams and Samuel Gorton work to pass legislation abolishing slavery in Providence Plantations, the first attempt of its kind in North America. It does not go into effect.[46]
    1677  Maratha Empire Shivaji I banned, freed and stopped import and export of all slaves under his Empire.[47][48][49]
    1679  Russia Feodor III converts all Russian field slaves into serfs.[50][51]
    1683 Spanish Empire Spanish Chile Slavery of Mapuche prisoners of war abolished.[52]
    1687 Spanish Empire Spanish Florida Fugitive slaves from the Thirteen Colonies granted freedom in return for conversion to Catholicism and four years of military service.
    1688  Pennsylvania The Germantown Quaker Petition Against Slavery is the first religious petition against African slavery in what would become the United States.

    Please see the full list of these movement against slavery here:

    https://en.wikipedia.org/wiki/Timeline_of_abolition_of_slavery_and_serfdom