The belief that autocracies will inevitably fall (or perhaps that "the arc of history bends towards justice") is hopelessly naive. Technology is a force multiplier with the power to entrench autocracy, forever.
Leaders of specific autocracies change, right (e.g. king got killed, but now we have new king), but governing structure persisted.
Most common people care for abundance and affluence. Any system that helps them arrive there is ok.
And that might actually work, if that were the only problem. But it's not. The deeper problem is that people work better when they get to share in the proceeds. People didn't work very well in the "worker's paradise". They worked half-heartedly, doing the least they could to get by, and production (and quality) reflected it. (This isn't exclusive to communism, though. Large corporations can have similar issues.)