I've taught professionally for some time. I agree that the quality of many in-person courses is worse than the best online classes. Many popular books are also

I've taught professionally for some time. I agree that the quality of many in-person courses is worse than the best online classes. Many popular books are also junk. It's very hard to judge the quality of teaching, because nearly all students of a non-catastrophic class will give good ratings. Few students will take the same material from more than one teacher so they can make comparisons.