Well, I just finished a great book called, "You Never Give Me Your Money", by Peter Doggett. The author STARTS with the Beatle breakup, and goes on from there to describe an absolute legal hell, bitter in-fighting, a dense thicket of corporate entities, and lawyers, lawyers, lawyers. Whew, a story of pure greed if I ever read one. Sad, but well done, aptly named, and recommended.
No matter what that book says; it does not diminish the achievements of The Beatles in the world of pop music. Just because Paul McCartney is a total idiot today does not mean he was not a great tunesmith/wordsmith when he was young.
Also, most Beatles fans stop reading about THE BEATLES after the breakup because whatever followed WAS NOT ABOUT THE BEATLES. Even Beatles fans know their post-Beatles music is pretty banal. Even though Lennon and McCartney wrote most of their songs individually, without the other's help (exceptions are songs like In My Life and A Day in the Life); they somehow produced better material as Beatles than as solo artists. Maybe it was the competitive streak.
Oh, yeah. I’ve always loved them. The book I mentioned rounded out their story for me. Still the best book about their songs is, “Revolution in the Head” by Ian MacDonald....several pages of discussion on each song, pre-breakup. At the time, it was fun listening to them experiment and progress with each album release, and their travels from the naive, to the political, to the banal. Great fun.
Maybe it was George Martin. I don't know if Martin produced any post- Beatles albums by any of the members, but the quality of McCartney's and Lennon's music suffered a precipitous drop post-Beatles. Harrison and even Starr were the only ones whose music was creditable after the breakup.