Wars are brutal. No doubt about that. Nevertheless the disagreement that you mention ("which people fall into this category and who is to blame") seems to run so deep even here in the West, that I wonder if some of those protests wouldn't end up in an old-fashioned pogrom, if they weren't thoroughly policed from the outside.
Existence of more-or-less successful slave revolts across history doesn't really say much about viability of slavery as an economic institution. I don't think my take is pretty wild. The historic correlation between industrialization and abolition of slavery is rather strong, and while we can argue about whether it was causative, the hypothesis is at least plausible.
"Wild" would be if I attributed abolition of slavery to something that is clearly uncorrelated with it, so, say, the Milankovic cycle.
