ELI5: What causes some guitarists to be revered so highly? What is the "special ingredient" that they have that others do not?

I love classic rock and have thought about this for a while now...what makes some guitarists so much "better" than other guitarists? I'm talking about guitarists that are often referred to as the best of all time (i.e. Hendrix, Clapton, Jimmy Page)...what makes them a notch above everyone else? I sure that there are plenty of guitarists that can play their songs just as well as them so what makes them so much better that they've achieved an almost god-like status?