I think it's more that people are designing things with the intention of never creating documentation. The analogy with books doesn't really work for me because of that. Books aren't user interfaces that are learned.

The main UI parts of books to learn are page numbers, tables of contents, indexes and glossaries. They're not necessarily intuitive but they are pretty universal and standardized.

The reality is that people will use the things they use the fastest. And not having to learn how to use things means people will use them more.