I agree with the above. I think it's a pretty safe bet that Jaco Pastorius and Miles Davis both new theory, but they were able to "step outside" with great success.
Just to clarify my feeling, I don't feel they stepped outside of the rules of theory at all. Everything they played was perfectly fitting with contemporary chord and melodic and rhythmic progressions - just the choices of how to play those things was far more inventive, and technically brilliant, and showy, and enjoyable, than when most other folks do it.
However it's not like they were simply playing in the wrong key all the time without knowing it because it sounded good to them...
if you think miles or jaco were playing outside (I argue they weren't since there is theory that fits with what they did) then try some 20th century music from the likes of Bela Bartok or dozens of other well known brilliant "classical" composers. Far, FAR more complex than anything jaco, miles, or pretty much anyone else in history has ever done before or after, yet it fits perfectly well within the rules of theory - as long as you account for specialty items like quarter-tone scales (Bartok).
So again - knowing theory helps prevent you from doing something that is simply wrong - and when it's wrong, it SOUNDS wrong, and also is wrong in theory.
Here is the reason why theory exists: to help us make music that doesn't sound bad, and to help us do it with and for other musicians.
The rules of theory were created, and evolved, because our ears like the sounds and need it documented so it can be communicated with others, and also to help us write more music that sounds good without having to randomly guess if this note or that note will sound good with/before/after this or that other note... instead we write down what we've learned and base future work on those writings.
That is music theory, and it evolves as we do and our music does.
It has absolutely evolved to the point (long long ago) where there is effectively a theoretic explanation for almost everything that someone out there in the world thinks sounds good.
However there are some things that simply sound bad - they get words like cacophony.
;-)