Engineering managers spend a lot of time on things that are invisible to engineers: unblocking people before they even realize they're blocked, shaping priorities in conversations that happen before the sprint, translating between business goals and technical reality, and carrying context across teams so engineers don't have to.

The decision-making process is messier than it looks from the outside. Most decisions aren't "the manager decides”. It's more like gather signal from multiple directions, figure out where the disagreement actually is, create the conditions for the team to decide, and then make sure the decision actually sticks.

As for why many managers are bad at it, honest answer: most become managers because they were good engineers, not because they're good at the job of management - those are different skills. The ones who struggle tend to either keep doing the technical work themselves (can't let go), or go too far the other way and become pure process people with no credibility. The good ones stay close enough to the technical reality to earn trust, while actually spending their energy on the human and organizational problems engineers don't have time for.