The issue is with lumping all learnings and knowledge transfer with protectable intellectual property that belongs to someone. (Hence the "property" part.)

Of course there's overlap. But the issue that people have with non-competes (especially broad ones) is that they effectively try to limit all knowledge transfer that may benefit a competitor directly or indirectly. Especially when this gets to a point of prohibiting people from working in a given profession or role for anyone else without any compensation, this seems wrong.