He kind of touches upon it, but there is a lot of value in being able to go into an interview and literally being able to say about a topic "I wrote the book on it." It's a tremendous signal to have overcome the hurdles of getting a publisher to accept you and print your book with your name on it. I used to have several guys on my team that had published books- and they were great, and were constantly getting contact…
Also, regarding "overcome the hurdles": those hurdles are now practically non-existent with various publishers. This results in books on the topic that should never have been published.
I could explain in more detail, but there's a lot of negative connotations with technical book authorship, which I work to overcome in such interviews and in roles. Does the author care more about working on their reputation than working for the company? Did the author only write the book to make an exaggerated name for themselves for the benefit of job interviews? (As you suggested in your opening sentence :-) I personally only write books when I'm already the expert on the topic, and it's a way to share my expertise.
Another interview I had years ago, after telling them about my first book, the interviewer said "so you know the theory, but can you put it in practice?" The assumption being "those that can do, those that can't write books." I was in a worse position for letting them know about it.
And of course, there can be positives for writing books. You are showing a willingness to share your knowledge with others. (You can do that in blog posts as well.)
Edit: added missing word "interview"