I recently tackled a book that was rather above my French reading level. It only took about half an hour spent fumbling with my Larousse before I plunked down $6 on their iOS app so that I could get back to reading my book. That weekend, my trusty old dictionary and I paid a visit to the used bookstore.
It's hard for me to imagine an information technology that's been more thoroughly superseded than the print dictionary. Electronic media make it faster to look words up in the first place, sure. But I also get audible pronunciations, and, if a definition includes another word I don't know, I can just tap on it to navigate to its definition. A print encyclopedia, you can at least sit down with a volume and just read it, and it's an experience that's sometimes more fun than surfing Wikipedia, by virtue of feeling a bit more random and serendipitous. But using a dictionary is always vaguely unpleasant; all you want to do is accomplish a specific task and then get back to your business.
The author is right. They really do derive most their value these days from being, in effect, large blocks of wood.