The comment with more words did a better job explaining the importance of brevity.
Discussion
Word count isn't the only indicator of good writing. Using more words than necessary is bad writing. A book can contain more than a single thought, and some people have reason to dig beneath the headline for some topics.
Rehashing what has already been written elsewhere is a waste of time, hence the book recommendation.
I've read many great books that were absolutely worth being written and read.
I use such knowledge to prevent people from dying at work, for example. It turns out that some topics need to be deeply understood and require more space than a tweet to teach. However, that doesn't mean a book should be 200 pages if 100 pages would do.