Your experience is wildly different than mine then. The worst professors I had were the ones teaching out of their own book.
In fairness I actually did have one good experience with this. I had a history professor assign some material he’d written about the civil war and both he and the material were fantastic. Ironically that was at the junior college. Professors become professors by publishing. I’m not sure why someone would think “wrote the course material” would be a feature unique to elite universities.