Everybody is self-taught. If you went to university (for example), the professor was there to set the curriculum and force you to study (things that otherwise you didn't know were important or didn't want to pick on your own). Teachers helping with a student's question is a very small fraction of learning. We learnt x because we practiced x ourselves.
And the ultimate university degree, the PhD, is all about learning how to learn. It's unlikely that you will continue to work on the project you did your dissertation on where you spent 3 to 6 years becoming an expert on in grad school. The point wasn't getting the knowledge, it was developing the skills to get up to speed on a new topic quickly.
Well, then how do we qualify "this", and help future expert-generalists immediately find a niche and start pursuing meaningful work? (Not that "work" is the end-all, because we hopefully work-to-live and not the other way around.)