That was part of the trouble. Paul always had heaps of stuff, and by 1969 George was getting a bigger and bigger backlog. There was no way those songs by either Paul or George were ever going to be used up getting four tracks on a Beatles album every year. So there was little choice but to do solo albums just to get the songs recorded. I can’t see even if the Beatles stayed together that they all could have avoided also doing solo projects.
They could have released 2 double albums every year
The trouble was John and Paul were increasingly headed in different directions musically. John loved harder rock songs like I Want You, Come Together, Dig A Pony, Paul was writing Maxwells Silver Hammer, TLAWR etc.
Ive always been a bit annoyed that The Stones stayed together all these years but The Beatles split 51 years ago. DAMN !!!