> Communism necessarily implies authoritarian government

What? Since when and in what way?

The common definition of Communism is where all participants are sharing the ownership of production and trying to remove things like money and financial class. Many ideas in Communism in fact assumes the absence of any kind of central government.

Then that the states that have tried "Communism" in modern haven't actually aimed for any of the original goals is less important. But let's not change meaning of words willy nilly like you did here.