I don't believe Marxism would work in practice, I believe you'd always just get a _different_ one percenter class composed of party leaders instead of business owners, but I'm not sure that it's actually been given a fair trial. To steel man their argument, communist countries always had the world's top economic and military superpowers like USA doing whatever to could to prevent communism from spreading. I'm no history surgeon, but I can't think of a time when it was tried without external interference.