Authoritarianism is a term that gets thrown around a lot, but doesn't actually have much meaning. As Engels explains here, authority is necessary for any complex organizations to function. The reason we see hierarchical systems emerge is due to the fact that fully complete graphs don't scale well. You can't just have everyone come to direct agreement with everyone else when you're dealing with hundreds, thousands, or millions of people.
The fundamental fallacy of antiauthoritarian movements is that power structures and authority end up being created organically without any checks and balances. Charismatic individuals gravitate towards positions of power and create implicit authority. It's much better to build power structures consciously and ensure that clear checks and balances exist up front.