A lot of less experienced employees don’t understand what managers do. There is also a certain personality I’d call “the geeky engineer” who thinks the same way.
Some things that are actually signs of an effective manager are hated by employees. Some individual employees for example need micromanagement or frequent manager involvement to make sure they don’t go off track, get stuck without telling anybody, or blow a time budget on something unimportant (eg a task is scoped at 2 weeks and they spend the entire first week playing with something speculative that may help).
A lot of managers are both highly paid and truly bad. I think a lot of businesses don’t do as good of a job vetting EM hires as they do SWEs the EM will manage. And I don’t mean that the EM needs to be Staff-level necessarily.
Even a good manager is incentivized to do things that are globally suboptimal (empire building, overextending) for career growth. This is also true of ICs though.
Personally, I think the biggest problem is the EM hiring bar though. Where I work has high standards and is very selective when recruiting ICs, but it seems like all that goes out the window for external EMs. I do think EMs deserve high pay and to be incentivized to do good work, but that requires a hiring process that better distinguishes between good and bad EMs.