Look over the history of self proclaimed "communist" leaders and they're an unlikely lot, particularly the two most "successful" ones. Stalin was an ex-seminary student turned revolutionary strongman and Mao was an illiterate peasant turned revolutionary strongman, both in heavily agrarian countries that each had to be aggressively industrialized before any kind of industrial workers paradise could even be possible. Neither of them was anything like a true political scientist or economist, so it is hard to be sure if they did not know or simply did not care communism was a non sequitur in their native lands. A century later and each has only begun reaching the point anything like communism as described by Marx is an option, but Stalin, Mao, Pol Pot, Castro, etc. etc. would have been perfectly happy to make Pastafarianism their path to power if it would have worked. Stalin might well have done so if he had not been kicked out of the seminary at the end, and Castro is such a hard core secular communist he still respects the Pope.

So, no, I disagree that historys verdict invalidates communism, because I do contend it has not been tried (for one thing, Marxism predicts a global worker revolution and subsequent government, which I KNOW has never existed.) I agree that it is a utopian fantasy that ignores humanitys moral weaknesses and therefore WOULD always fail if attempted, but that does not mean it has. That various dictators have attached themselves to communist rhetoric to sell their brutal authoritarianism makes them opportunists, not communists. East Germany called itself a "Democratic Republic," too; so what?