I'm not too sure about the 'comfortable margin by which they outstripped their contemporaries' line.
I think at various times in the 60s, Dylan, The Stones, Jimi, Aretha, The Kinks et al were perfectly capable of keeping up or even emulating The Beatles.
I don't want to derail the thread and get into another p*ssing match, but I cant agree with the names being dropped here. Dylan wrote masterpieces of popular music early on and showed the Beatles how a story can be told through song, but musically, I don't feel he was blowing people away after 65'. Hell, his followers almost fainted just because he picked up an electric guitar. I look at old Bob as a folk singer and writer and not much of in innovator after the early 60's. There's a reason people said the Stones did everything the Beatles did,,,,only 6 months later. Love the band but don't see anything there that tops the Beatles. Jimi blew the scene away when he came along, but truly was a one trick pony. If you dig distortion, long guitar solo's, sloppy music, and songs that sound the same, he's your man. For me, a little Jimi goes a long way. Aretha sang other peoples music. Great voice, but what did she contribute music wise? Now for the Kinks. One of my favorite bands ever. I would put their 5 album run of 'Face to Face' through 'Lola Versus Powerman' against anybody,,,,,,except the Beatles. The thing about the Kinks is that they'll have a song that dazzles and amazes you and then the next one comes on and you wonder how in the hell this garage band ever got a record deal to start with. Great stuff, but nothing that I would put against the Beatles high notes. Whats the Kinks greatest song,,,Waterloo Sunset maybe. Is that their crowning achievement? The Beatles have a lot of Waterloo Sunsets.
Sorry, rant over.