[sarchertech]

People read books because grabbing bits and pieces from blogs and tutorials often means that you end up with holes in your understanding that you don't know are there. Books are also a nice place to start when you don't even know what blog posts to read.

Tutorials are great if you want to learn how to use library X. I prefer books if I want to understand the problem that library X solves. Of course that's a sweeping generalization.