>My understanding is that they still try to limit the number of managers

IMHO this is really the point. Somebody has to hire devs, run the evaluation/promotion stuff, facilitate communication to/from upper management, and so on.

I've just never been to a place that couldn't do that with 1/2 to 1/3 of the EMs they have. For whatever reason the standard is one EM per team. A better ratio is on EM per 2-4 teams.