> Besides, a lot of non-fiction just isn't that great. Many books should have been a blog post. These books are rarely a rewarding experience for me, unless it's from a rare combo of historian and good writer.

Many non-fiction books are essentially PR material for the author. They don't write these books, because they have interesting thoughts that are too complicated and long for a blog post, but because their career plan involves being some kind of a public intellectual and writing a book is a part of that. They often have a single idea, that in itself might be an interesting one, but it's simple enough that it could indeed be entirely fleshed out in a blog post or an essay rather than a book.

This is helped along by the number of people willing to cynically offer up a blurb, or even a glowing review, to something mediocre or seriously flawed that they may not even have read. I'm sure the blurbers think they're just doing someone a favour (and/or playing the game so that they will receive reciprocation), and the reviewers are probably less often crooked than simply busy/lazy, but it all goes to make it much harder for good, substantial work to stand out.