I'd argue the opposite: it's the technically-savvy people who got promoted to management/leadership positions, while lacking the people skills, the strategy chops, and the basic understanding of business realities - these are the truly incompetent managers.

But you need to be able to promote good technical people or they will finally leave and you ll be left with gif managers an no one good technically to manage.

Gif managers?

Sorry bad spellchecker. Good managers.

Where do these clueless managers come from?

Somewhere amongst the 90% of emloyees that do not have a strong opinion one way or the other?

Many times, they were technical people/engineers who weren't that great at the technical stuff, but were really good at networking and self-promotion, and talked their way up in the organization.

A boss doesn’t need to be technically competent to a degree that they make important technical decisions. They just need to understand things to a degree so they can trust and delegate.

And tust is a two way street. It requires effort from both sides.