The number of tutorials has to do with the popularity of a language and the general level of competence. The author is talking about a user interface, not how-

The number of tutorials has to do with the popularity of a language and the general level of competence. The author is talking about a user interface, not how-to books, so it's hard to apply the principle to programming. (How a PL implementation is documented is a a little similar but not the same.)