Nestor Makhno, on the other hand, is generally recognized as an anarchist, and yet he too had argued for centralization of power.

Well I think traditionally to indicate a period before the Cold War. While Stalin was leader of the USSR he was hardly a communist as Trotsky himself would hove told you, I believe his term for it was "degenerate worker's state"

There is libertarian communism, and some actually outright reject authoritarian communism as actually being socialism.