Yeah... I'd argue, from my anarchist view point, that Marx nearly had it. Humans and unjust hierarchies have existed longer than economics, so, I feel that to be an oversight on his part. To my thinking, economic division is a mechanism of creating or sustaining a hierarchy of classes. The problem isn't purely economic nor sociological but both, that is socio-economic (like electricity and magnetism are make up electro-magnetism).

Economics (wealthy disparity), religion (castes), and violence are all mechanisms used to separate people into hierarchies of power and allow a small number to exercise power over others. Any hierarchy of societal power results in repression. The Soviets betrayed the Makhnovists, rolled tanks into Czechoslovakia to prevent self-determination, and committed genocide via forced relocation of "problematic" ethnic groups to destabilize any resistance to their hierarchy of power that made all subservient to Moscow.