you've got to realize that even thought the Beatles aren't terrific(but they're good), they weren't famous for just being musicians. they redefined the recording world with Sergeant Peppers Lonely Hearts Club Band, they changed a lot of stuff about the guitar.
they just changed a lot of thing and broke down a lot of barriers. you don't need to a virtuoso to do that.
even a lot of famous guitarist say that they wan't to be like the Beatles, but harder or faster or something. they wanted to emulate their sound.
so the Beatles WERE a very very very influential force that changed a lot of things.