The issue they can't accept is human nature. Communism on paper is awesome, but the overreach needed to maintain it is always inevitably corrupted and abused. Every Time. Capitalism sucks too, but it at least puts the powers at be in a constant bid for it which essentially keeps it from cascading to a point where it murders a nation. Communism just sort of gives one person the keys and asks them nicely not to take it for a joy ride. Which is like really ironic.