I was thinking about this the other day. I'm of the opinion that the main problem with Socialism or Communism is exactly the same problem as with Capitalism or "Free Market" economics.
Human greed.
They're all viable theories of how to structure a society, but they all fail when the people in power decide to put their own interests in front of the needs of the general populous.
Capitalism ends up being better because it usuallytries to have a separation of powers between those who control production resources and those who control policy and politics. In real-world Socialism and Communism, they are the same, allowing for greed to have a much harder impact.
Most forms of socialism are entirely compatible with private enterprise. Totalitarian media and production control like the Soviets used, yeah, that's different.
