no; accelerating the split of the Lennon-McCartney duo, along with dissolving the Beatles, was probably a net gain for music.

I'm considering the resulting solo careers of each musician as positive results, and ignoring the "contributions" of Yoko herself; so I guess the way I set up this calculation, it's almost impossible to reach any other conclusion, unless you have some high confidence that the Beatles staying together would have produced more good music, rather than just more of their acceptable boy-band pop-rock.