Managers that can't do are generally shepherds. Only sheep follow them.
Yes, it's good that managers can know a lot about a broad amount, but they should be skilled enough to dive fairly deep and realistically be expected to jump into anyone's job.
Otherwise, you're hiring an administrator or a non-technical manager.
And there's a place for that, but not one I want to be near.
I see nothing wrong with a manager who is technical but can't take a deep dive into the code.
A manager's role could be to decide strategy, priorities, budgets, inter team communications, working with the customer etc. the biggest thing I want from a manager is to hire good people and to trust them with the "how". My manager decides the "what" and "when". He leaves it up to his team to decide the how.
"strategy, priorities, budgets, inter team communications, working with the customer" is 90% of how. Your manager just presents these things as if they're not.
Yes, it's good that managers can know a lot about a broad amount, but they should be skilled enough to dive fairly deep and realistically be expected to jump into anyone's job.
Otherwise, you're hiring an administrator or a non-technical manager.
And there's a place for that, but not one I want to be near.