I think "no managers" approach can work only for tiny organizations. Rigorously hiring self-motivated people might delay the need for managers somewhat but at some point they are inevitable. Once managerial layer is in place, it is looking to grow itself and eventually that growth becomes detrimental by slowing down the project delivery. Different corporate cultures and initial trajectories affect the speed of this evolution, but it seems like every org more or less follows this path if we're looking at the span of decades.

> most organizations have an appropriate amount of managers.

technically true, but what would be the measure? if only we could check the alternative timeline with less managers.

I would not be surprised if quantity of managers in any org is asymptotically approaching the maximum number possible while the org is still able to produce any output.