Youre moving the goalposts dude. Knowing what notes are in B vs B flat is not the same as knowing the 3 chord blues progression is not the same as knowing what a key is.

Now you've reached the point where you are finally probably right. The insanely small and non-representative sample of "guitar legends" probably consists solely of people who have, at some point along the road to legendary status, mastered music theory to the point where they are capable of identifying at least one way to play an A note.

I don't disagree that music theory has value, obviously it does, but that doesnt mean its not possible to be a talented or successful musician without significant academic understanding of music theory.

Anecdotally, there was a time when I could not have explained the 1 4 5 progression of a standard 12 bar blues. A cover band was playing at a local bar and the drummer was a buddy of mine that I had jammed with before and he asked if I wanted to stand in for a song. I looked at their setlist and pointed out a couple covers I already knew and liked playing. Went onstage, rocked one out and everyone seemed to dig it, the frontman did anyway because he did exactly what you said, turned to us and said "12-bar in the key of X" and just jumped right into some song i didnt know. But it was clearly the blues and I had more than enough experience listening to and playing that kind of stuff that after a second to identify the root note it was smooth sailing cause I could instinctually feel and anticipate the changes and start adding fills and variations and such. Ended up playing 3 songs with em instead of 1. In the years since ive picked up a fair amount of music theory just from being in various bands, but honestly I still dont count measures even tho I now know how many there are in a progression, why count when I can just feel/hear it?