Well, Yoko One stunted the Beatles' interactive development, for example, during the White Album sessions, and after that, all that was required then was the Beatles to be trapped together for long enough for them to have enough of each other, which happened in the Get Back sessions.
But of course, if it wasn't for the Get Back project, we wouldn't have Let It Be. And if it wasn't for Yoko Ono, we wouldn't have the Ballad of John and Yoko, would we?
A RETROSPECTION:
A lot of things contributed to the Downfall of the Beatles. But the best way to remember the greatest band of all time is not by recalling their Downfall, but rather their uprise, and the music they recorded. As long as we have their music, we can live as though they never split up at all, and still live by their words.