A large part of the Beatles breakup was the fact that they had stopped touring, having done their last concert in 1966. They had concluded that there was no way they could duplicate their studio sound live. I mean, 8 tracks - - 8 tracks! - - how could a band be expected to duplicate that in concert?
Without regular gigs to keep them together they more or less went their separate ways, even as they continued to record some of the greatest music ever, like Yesterday and Today, Revolver, Rubber Soul, Sgt. Peppers, Magical Mystery Tour, Yellow Submarine, the White Album, Get Back (AKA Let It Be), and Abbey Road.
Good analysis.
See The Stones, as to what happens to your legacy when you stay on too long....The Beatles are as popular today as ever, because they knew when to quit, before becoming a parody of themselves.
Actually, they quit touring because of the cost and the mayhem and the fact, with the equipment then, no one could actually hear them live.
It was a simple business decision because, as Elvis showed, it was cheaper to make a movie and thus create music videos to promote albums. Touring back then wasn’t as big a deal as today.