You're making a huge mistake when you say that. This sort of snobbishness is really bad for art. Great art is always connected to the lowly and the popular. Disdain for that which is not "advanced", imagining barriers between high and low, is associated with nothing so much as creative exhaustion. It's the mentality not of the artist but of the critic, and the second-rate critic at that.
It's ironic that you would pick a couple of jazz musicians to illustrate this, since for most of its formative history jazz was derided as a vulgar form. Only in later stages was it championed by the priests of "advancedness". This is a sign of decadence. When the Davises and Minguses appear, that is the late-blooming of a genre, and by the time the scholars move in, the muses for the most part have moved on. (Which is not at all to say that Davis and Mingus aren't great artists.)
An awful lot of performance involves skills that are NOT addressed by music theory -- basically everything that distinguishes a mechanical MIDI performance of some piece from an real performance by a professional is not part of foundational music theory.
There's also a great deal of ground that music theory formalizes that long-time musicians will grasp intuitively (but be less able to discuss, of course).
It's ironic that you would pick a couple of jazz musicians to illustrate this, since for most of its formative history jazz was derided as a vulgar form. Only in later stages was it championed by the priests of "advancedness". This is a sign of decadence. When the Davises and Minguses appear, that is the late-blooming of a genre, and by the time the scholars move in, the muses for the most part have moved on. (Which is not at all to say that Davis and Mingus aren't great artists.)