technical skills are necessary to make educated decisions and judgments. Managers on high tech projects without such skills blindly shuffle people between roles usually base on which person is nicer to talk.
But there are many people to make an organisation work.
There, experts provide their expertise, managers make calls (hopefully for everyone - that's also part of their job, informed calls).
If the call was wrong, you can question & identify if it is either the manager's judgement that was debatable, or the piece of expertise provided, or both. And then decide what to do: change the methods, change the role, change the teams, move the people.
If you have a single person being the expert and making the calls, all you have is a bus number of 1.
> you can question & identify if it is either the manager's judgement that was debatable
You are probably referring on some VP level person, so I think they usually have even lower expertise, and will just fire manager who doesn't deliver, which is correct, VP shouldn't dig to such low level of execution.
Of course knowing enough about the product and space is important to make correct technical decisions as a manager. That goes without saying. The point is rather that the goal of a technical manager is not to come up with all of the answers, but put the right heads together to answer tough questions.