Earlier quoted context omitted.
I'm not sure how parent became the top comment, but "music theory" is absolutely appropriate here. This terminology is commonly accepted by musicians, educators, and practitioners. OP's link could say "western music theory", but that seems unnecessary given the audience. Secondly, why would you call this junk? This is actually very useful for people learning to play, and for those who want to understand the basics of…
Knowing how to spell doesn't make you a writer. I think the parent is trying to explain that there's a cultural bias and inscrutability with respect to how music theory is taught. Does learning a notation system make one a theorist? One can be a western musician in, say, a jazz tradition, understand theory, have theories and play music and have never used the system of notation explained in the otherwise awesome comi…
What system of notation do you think jazz musicians use? I don't think you'd have any luck trying to find employment as a jazz musician since at least the 1930s unless you could at least read music, and be fairly good at sight-reading as well. And as far a composing and arranging? Those guys not only knew tons of theory, but very consciously developed their own extensions to it. They were very familiar with Western classical music, as well as Blues.