The truth isn't that you don't need a teacher. You may be able to learn everything from a book or solitary practice, like yourself. But others probably can do that sometimes, may sometimes need a teacher, may sometimes need to discuss with peers, etc. And I don't mean that some people are visual learners, or readers, etc. I mean that people learn different topics in different ways, on different days, with different contexts, etc.
I think the cultural norm should be that if one way of learning isn't working for you, try another way. Practice, read it yourself, ask a friend for help, get a tutor, whatever you need.
Absolutely, I'm not saying teachers are never useful or needed. I'd much rather have a conversation with someone familiar with a large codebase to get a feel for it than diving in and creating assumptions. But the bad advice is that a teacher of some form is essential, and that's wrong-headed, and it paralyzes people when asked instead to not just solve a well-rehearsed problem, but actually to discover the problem that needs solving.
I think the cultural norm should be that if one way of learning isn't working for you, try another way. Practice, read it yourself, ask a friend for help, get a tutor, whatever you need.