NEVER work for someone who is incapable of doing your job. To do so is to construct an extremely dangerous, brittle situation.

This doesn't mean they SHOULD do your job, or HAVE to - just that, they could - and are therefore qualified to manage you - while you do it.

The Peter Principle is real, and legitimately a source of massive waste and inefficiency in the world. Simply refuse to work for someone that cannot do what you are expected to do - and you will be building a better organizational framework.

The corollary is interesting: don't try to manage someone if you can't actually do their job, either.