Interestingly though attorneys and accountants charge by the hour to customers. So their individual value to the group is easy to quantify and measure.

And while they may have support staff, they typically "work alone" in the sense that there's one partner per account, so very little oversight or management is needed.

The primary purpose of this "collective" is to create a "brand" of sorts. Ernst and Young has more prestige than say Franklin and Franklin. This draws in higher paying customers.

I feel like there are sufficient differences in this kind of business to a typical software business that the comparison is not especially useful.

Which is not to say that a coop can't work, just that the comparison to accountants and lawyers doesn't work.

Attorneys: associates, junior partners, senior partners, managing partners, named partners. Does not look like flat structure to me.

Like I said, growth is hard.

My brother is an attorney in a small practice of 6 attorneys. They are all partners, share ownership, and rotate who the managing partner annually.