I would disagree that "it's not a theory in any sense of the word". There is an established sense of the word "theory" in which its meaning is derived from how

I would disagree that "it's not a theory in any sense of the word". There is an established sense of the word "theory" in which its meaning is derived from how it contrasts with "practice". Theory vs Practice is a fairly common dichotomy. In music of course, the practice part is just playing. The fact that this sense of the word has less precise boundaries than the notion of theory in math/logic/science doesn't render it totally useless IMO.