I'm going to rip into your examples not because I want to, but because this is the only comment with concrete examples I can use to show the fallacy of needing managers. Apologies.

> Prevent other teams from reaching in and randomizing our priorities, work on promotion plans for anyone seeking promotion, manage customer/partner team relationships, ensure everyone has balanced feedback regularly, mediate disputes, collect information to manage upwards so we can still be funded, advise on team process but never mandate it, facilitate accommodations, manage poor performance so the team isn't dragged down, try to consolidate and clear meetings from calendars across the team.

Now I won't pretend that these are not real problems that companies have, but I would argue (from my own experience) that they are not problems that all companies _must_ have. A company I worked at did not have these problems — _without_ a manager sorting them — and we had literally hundreds of engineers. Granted, this was a single company, and I've not seen it happen since, but if it can happen even once, then it proves the point.