Hey Pop, Just my opinion but I think it evolved during the early rock and roll days and is fan based. In other words music fans started this and not the musicians themselves.
Guitar players have people who influenced them, and how many times have you said "I could never play as good as so and so".
That doesn't mean that you want to compete with them you just want to maybe emulate their skill.
I can guarantee that it was a music fan who painted "Clapton is god" on that wall and it wasn't Jeff Beck. Ben