The main reason books are better is because they are harder to write and produce. The person making the book actually has to invest a lot of their time in making it happen, unlike a blog post.

I've seen lots of articles on hacker news (and other places) that is "PART 1 of..." which does the introduction to what they plan on teaching, and then it just dies right there in the land of "PART 1's"

With a book, if you stop at part 1, no one is going to publish your book.

Another thing about books/web, is books go MUCH deeper into topics. It seems like 99% of the content on the web is "INTRO to xyz" but never "Advanced xyz"

Books are also broken into logical section so you have a learning path you can progress through; not just random content that you are to piece together yourself.

So, yes, very good advice; if you want to learn something, read the book.

blog posts are more just advertisements for buying an actual book.