Have you seen the opposite? Where Product handles the Product, Architects and Leads handle Technical decisions? All Engineering Managers are left then are metrics and localized HR. They end up managing multiple teams, since its hard to justify such a small job of managing a single team for such a large title. They end up getting overloaded on teams, and start managing by dashboard, because talking to all 30+ of your reports is impossible.

The most useful job they can do is to take on responsibility. When everything becomes decisions by committee, at least one person has to occasionally take the reigns and say "Yes, do that one and forward." That is their real value in big companies from my standpoint. The issue is when they are all concerned about their management, defer the decision upwards, and now you have a King who must approve everything.