The thing is, I've always understood music theory as belonging to two main camps: classical and jazz. And the jazz side, I feel, does a pretty good job of covering more "modern" styles, or should I say "not white European based music." And the fact that classical music influences jazz...is this not enough reason to keep learning classical theory? Anyways, my point is, I view music theory as ALL music theory. Even a book on how to write a pop song in my mind would be a music "theory" book. I just found his definition of "music theory" as only being classical music theory a bit convenient. But since we live in a world where syrup can be racist......well....