Being good at content is not the same as being a good teacher of the content. I think all of us can remember a teacher we had in school that was super smart in their subject but couldn't explain it to anyone in a way that was comprehensible. It is 2 entirely different skill sets. Some people have one some the other and a rare few have both.

The problem is how to find the people that both understand it and can explain in well. Arbitrary requirements just dont work well.