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?
But the point remains: Just reading the book, as in consuming page after page, is not enough.
Indeed, books do not "work." Dedicated students work, and by doing so, they will learn.
Not that all book that claim to teach skill actually teach it, but plenty of them do.