I think, some people are born with more natural talent than others. Just like some people are better at running than others etc. Because of their natural talent, they may not need to know any theory, or at least, less than others. For those people that don't get born with the musical super gene, theory will help them progress faster.
It also depends on the music you are playing. If you play mainly all root notes (not necessarily a bad thing) then theory probably isn't needed as much. But if you want to get hired for Dream Theatre, you will need to know it inside & out.
That being said, I have found (IMO), that so many people are getting right into jazz theory, they really know their stuff, but they all sound the same to me. Of course there is slight differences, phrasing etc, but over all, if you gave them the same gear (so you couldn't tell them apart by their sound), gave them a II, V, I to play over, I probably couldn't tell who was who. Of course, I am not saying this of ALL jazz trained muso's, but if you go on YouTube & have a listen, it is hard to find a stand out with their own sound, style, voice (musical).
You are only one fret away from a right note, so as long as you have groove, can you just bluff it??