You're focused on reading as a way of ingesting ideas and culture. The author focused most of his article on the process of reading, and its long term neurological and physiological effects on the reader. In other words, he's not so much saying that people don't know enough, it's that they've lost the ability to focus for long periods of time. It's an attention deficit argument, not an illiteracy argument.

(I think the article is poorly argued and doesn't support itself well; I also think it's probably observing something that is worth continued study)