By "music theory books", I believe the author means "Literature which attempts to explain biologically why harmonies sound pleasant". My experience with this is

By "music theory books", I believe the author means "Literature which attempts to explain biologically why harmonies sound pleasant". My experience with this is that 1) Much of this literature is indeed in inside books which also discuss the "cookbook" parts of music theory, and 2) It's shocking how much incorrect, unscientific nonsense there is in these texts, and 3) There's nothing close to a scientific consensus about why humans and animals nearly universally feel good when hearing harmonious sounds. The author is attempting to answer that question, and I think his initial complaints are perfectly valid.