>as a medium, books are surprisingly bad at conveying knowledge, and readers mostly don’t realize it.
I posit it is not that books are bad at conveying knowledge, it is that people are bad at absorbing abstract knowledge they don't put to concrete use, and that people often read non-fiction books which have no practical application in their lives. A teenager in Africa can read a book on electronics and build a generator. He learned, because he employed what he read. A man can read a book a book about building a cabin and build a cabin.
Effete upper-middle-class desk-jockeys will happily read a treatise on particle physics or ethnography but are helpless to recall it a month later because the knowledge had no real impact on their lives and thus the brain cleaned house and threw it out.