The essential concept is that overthrowing the current order is the most authoritarian thing you can do. It is imposing your ideas on the overall system and it will require coercion. Mutual liberation requires the imposition of a political program that runs counter to the behaviors and interests of the current ruling class. The class with the cops, the armies, the money, the trade. You will have to oppress them or they will kill your movement in its infancy. They will invade you and kill all of your friends. So you will fight them or die and you will have to institute policies against them or die. We do not have the privilege of living in a world where the material forces against us will give fairly give in to popular will or do what is right or not bomb is and our children.
I would add that "authoritarian" is a label that is applied so selectively that is it actively misleading. It is usually a means by which to spread anticommunist thought that ends up reinforcing the far more authoritarian status quo. If one does their best to excise this selective use from themselves, we then end up talking about he first point of brass tacks of what choices are offered to us when we have our own anti-capitalist nation-states. They are, unfortunately, limited given the relentless violence and maximum pressure from imperialist nations. Nuclear Armageddon was only prevented by a far more humanistic socialist bloc on several occasions. The imperialists were ready to go and pushed right up to the limit. There are many examples of this tendency, but Korea is a salient example. They bombed every single population center in the north. Genocidal. It wasn't even their country. It was just to "contain" the Korean left, which was otherwise going to win without US imposition because it was, organically, more powerful.
What is more authoritarian than a bombing campaign that destroys your entire village?