> And precisely, therefore, they must not continue living under the present system which permits them to oppress and exploit one another.

The whole issue is that every system permits "them" to oppress and exploit one another. Capitalism works because it embraces our instinct to do this and tries to turn it to everyones advantage. Communism has no answer for what to do about this problem. Capitalism is designed to succeed when people are selfish, and it turns out most people are. We might not be good enough for capitalism, but we sure are bad enough for it.