The point about Credibility is interesting. There's something about someone who's written a technical book that automatically seems impressive just because writing a book is hard, and it's easy to assume that the person knows a lot. A long time ago I used to do technical review for a publisher on books about code. It was pretty obvious that some authors didn't really know what they were talking about. They knew enough to write something, but there were always a lot of mistakes.
I think many technical books are written to act as a 'proof' that the author is credible and knows their topic well rather than as an exercise in serving the reader or an attempt to make money. Tech authors know that they've not going to make much. It's more an exercise in vanity and improving job prospects. The author doesn't really need to be right. Especially "Beginner's guide to X" or "Learn X in 24 hours" books, experienced and knowledgable developers won't be reading the book to criticise it, and new developers who buy it won't know it's poorly written, so an author can write any old junk and still claim to be an expert. Consequently I've stopped being particularly impressed by people who have authored books on their resume.
I think many technical books are written to act as a 'proof' that the author is credible and knows their topic well rather than as an exercise in serving the reader or an attempt to make money. Tech authors know that they've not going to make much. It's more an exercise in vanity and improving job prospects. The author doesn't really need to be right. Especially "Beginner's guide to X" or "Learn X in 24 hours" books, experienced and knowledgable developers won't be reading the book to criticise it, and new developers who buy it won't know it's poorly written, so an author can write any old junk and still claim to be an expert. Consequently I've stopped being particularly impressed by people who have authored books on their resume.