You've described a solid method to interviewing.

I think your point about people who read books could be better described as people "intentionally learning" and using "self-directed learning". The sources of that learning are extensive and not limited to books or online courses. You could learn from a mentor, by trying out things yourself, by reading source code of open source projects, reading programming blogs, etc.

The underlying theme is that the person is intentionally trying to learn and doesn't require hand-holding or pressure to do it.