[duped]

As another former music student turned engineer I think the breakdown comes from the misinterpretation of "rule" which could better be called "practice" or "style."

My barely-above-pedestrian take is that music theory is an analytical exercise that tries to separate order and patterns from the spontaneous discovery of what "sounds good" in a piece so that the practice can be reapplied to another. The rules of theory aren't really rules, they're a taxonomy of practices exercised by composers and musicians that came before us. And what works changes with the taste of audiences.

A great example to me is parallel octaves, fourths, and fifths. You would be hard pressed to find popular music composed in the 20th century that didn't make liberal use of those, and the technique for writing and playing them is so commonplace it makes no sense to call it a "rule" to avoid them.