There have been plenty of Capitalist dictatorships to stop Communism. The deal with dictatorial states has less to do with their internal economic policies, and more to do with world superpowers intervening to advance their own interests. You can see this with the Eastern Bloc having strong ties to the U.S.S.R. instead of having their Communist ideas being brought up within their own state, and the Deng being Soviet-influenced. Yugoslavia is a very good example of a Communist state done right, as is Vietnam; the former was deemed false Communism by the U.S.S.R., and the latter was left alone. There’s also Cuba, which again, is not under the U.S.S.R. You can also see Capitalist satellite states being given arms support by the United States, which really makes it far less about the nation’s own choice to be Capitalist or Communist, and more about their status within the Cold War.

I do agree that Communist economies aren’t perfect, but it’s not as simple as G.I. Joe.

TL;DR No economic system exists in a vacuum; nations act and are acted upon each other like cogs in a giant machine.