Managers are here to accommodate the need for cooperation, while compensating for lack of telepathy.

Put two people with a lot of expertise in different domain. Require them to come up with a solution to a problem you have.

That's three people. You'll get at the very least four opinions about each and every step.

Scale the complexity of the problems and the number of people.

You end up with full time jobs consisting purely in routing information from brain A to brain Z.

Unfortunately, the skills to do this job are never properly taught, but learnt in the job. (MBA don't teach management - they either teach the mechanism of some administration, or ways to get rich consulting.)

Problems occur because we conflate management, supervision, decision making, strategy setting, etc...

P.H.B. is an antipattern, a caricature, a stereotype like all other : it's funny cause there is truth to it. But we are by no mean condemned to fulfill our stereotypes (should I remind all engineers here about the stigmas attached to nerd in the real world ?)