The main issue is that they communism is economic policy, NOT social policy. While they do go hand in hand people often conflate the two. Many dictatorships use communism as a way to control the people but that doesn’t mean that communism leads directly to dictatorships.
You can’t have a communist economic policy without being authoritarian. It’s human nature - once money is removed as a motivator, society breaks down unless you motivate people some other way (not being sent to the gulag).