Some books explicitly claim to teach you a specific skill. And some people have that general expectation towards books. This is what the author criticizes, as I understood their points.
I guess a lot of people don’t do that. They skim through a textbook like it’s a boring novel and they make a few notes or they highlight everything or they fill the poor book with sticky notes in a multitude of colours. Anything but doing the exercises! And then is it any wonder why they forget everything a year later?
Indeed, books do not "work." Dedicated students work, and by doing so, they will learn.
But the point remains: Just reading the book, as in consuming page after page, is not enough.
Not that all book that claim to teach skill actually teach it, but plenty of them do.