Not easy to accept, I know, I had a hard time too. But it's the truth and when you look at it, the fact are clear, the growth is clear, the system is clear.
While China has a lot of other problems about racism or sexism, they are headed the right way in the direction of anticapitalism, and you just have to observe the result.. they kinda speak for themselves.
Cuba could go the same way if the US were not trying to exterminate them, the Soviet Union was too young to quick to succeed, there had so much other problems and I ahve sadly not enough data on North Korea to talk outside of the obvious authoritative shell.