You don't believe some training is at play here? If you get used to reading isolated snippets of text over and over and over, you might think a tweetstorm is a better medium than a book, but it probably has a far worse useful content ratio, and I can almost guarantee you that you'll have a harder time remember 90% of that social media than you would in that "less consumable" book that nonetheless is structured in a way to facilitate learning.

People have been taking books with them, reading parts, placing a bookmark, and returning five minutes later for centuries. Is social media really more consumable or does it taste good and we've gotten used to it?