Maybe the book is one page long, with URLs to Google and Mobilread?

More seriously though: a lot of people prefer everything to be in one place. A well written book does that while information tends to be scattered across websites or forum postings. Other people find books to be more reliable sources for information, and if you look at the banter back and forth on a forum that's partially true.

I'm not going to buy the book because the type of stuff covered by that sort of book is the sort of stuff that I could figure out on my own (without looking online). But I think it's kinda silly to dismiss the book simply because other people may be interested in it.