Authoritarianism comes with organizational structure, right out of the box.
Cooperativism (or horizontalism or anarchism or whatever you want to call it) tends to define itself by the rejection of hierarchies -- and since nearly all organizational structures we're exposed to are hierarchical, we tend to reject organization as well.
We need to focus on working out non-hierarchical ways of organizing.
I do have some ideas... [points at hobby-horse on the mantlepiece]