if they didn't have the imagination or creativity to come up with intricate music without being taught theory, sure school would help a person like that.
other people like Allan Holdsworth for instance, creates some of the most intricate music ever and doesn't read or write standard notation.
he plays with guys like Gary Husband and Chad Wackerman and conveys how he wants things verbally and by listening to demos and rehearsing.
I'm not trying to put down learning theory at all, just shooting down the notion that people who don't know theory are somehow disadvantaged.
p.s. LOTS of people go to music school to try and be a rock star
I said this before but stand by it
Probably been said already but theory is like a map. There are many ways to get from a to b. but if you are in a stange town and don't ask directions then you could be wandering around for hrs before you get the result you want. Wandering aimlessly can be a pleasure too and give great unexpected things to you but with a map you don't just see a to b, you see a to b and every possible detour route to get from a to b before you even set out on the journey .
Or bluntly put you don't need to play a note before you already know how it's likely to affect the musical story you are telling!
I do most of my practicing in my head now. When teaching I only need to pick my bass if it is important to demonstrate
You can't teach creativity but you can open the doors.
Theory is also a great way of effective communication.
If you went to a jam night and some shouts 2,7 , 5 , 1 in d then knowing theory you can jam perfectly in tune and melodically before you have even hit a note.
Theory has nothing to do with phrasing which is really the main difference between a good player and a great player. If you miss the first point/analogy I've just made and it goes over your head then I have no further help for you.
But don't confuse reading with theory as so many people do.
Reading is like reading any language . You don't need to be able to read a single word to converse perfectly in English . Reading does not affect your ability to talk but if you can read then just like the internet you have access to every piece of information ever written down.
In English , how to speak , when to use nouns, plurals, Noun, pronoun, adjective, verb, adverb, conjunction, preposition, interjection , . These too are like the theory of music. Don't need them to speak English but you'll sound like you dont have a grasp in the language or will struggle to articulate your thoughts in some situations.
Also if we apply this to one thing say..knowing your modes. Just because something is say Dorian in c (d Dorian) doesn't mean you are limited by anything at all. You can still play those notes with any preference, in any order with any phrasing and hit all the chromatics around it or choose any other relative mode and every chromatic between . It just means you can accent/draw attention to the in tune notes more. If I'm in c Ionion I can run a lm augmented or whole tone scale from it and still make it work over most styles of its phrased right.
Meh! Give up after this!