If there's an abject lesson here, it's this: Brian Wilson's fragile psychological state and utter lack of support from his bandmates hamstrung him, preventing him from reaching the creative heights he might have otherwise achieved. Pet Sounds and Good Vibrations depict an artist creating music that no one had ever before imagined. In contrast the Beatles' esprit de corps was never higher than it was in 1966. The creative roll they were on throughout the following year would not have been possible had they been suffering through a similar level of dysfunction.
Robert Rodriguez in Revolver: How the Beatles Reimagined Rock 'n' Roll (p.77).
For more on this check out my post Why Wasn't Brian Wilson As Successful As Lennon and McCartney?