"Academic" music theory can be rather strict in many ways, but once something has been accepted into the "standard" curriculum, anything goes.
Case in point - Jazz
A now "accepted" form, that is both freeform AF, yet highly complex where certain "rules" must be observed.
Stockhausen and Varise etc
It is "curriculum", as freeform as the wind, and won't really survive a shenkerian analysis.
A kick, a clap, a bass note (note: lack of plural) and a monotonic vocal sounding the same note as the bass.
I IV V or I vi IV V played -strictly- with powerchords.
Or, 2 bare notes alternating over a single drone note.
It's totally possible for our convential theory to cover -all- this ground, but it is starting to look a bit frayed at the edges, after all this time