I’m a huge fan of The Band (especially the “Brown Album” from ‘69), but the fact is their prime was very short. ...around four years (from “Music From Big Pink” through “Stage Fright”). Robbie saw the writing on the wall.
Bob Dylan is the only guy to last nearly a half century with little to no drop-off in (extremely high) quality songwriting and recording. ...although even Bob went through his dry spells.
According to Levon Helm's book, This Wheel's on Fire, after Robbie decided to take credit for writing all the hits, on the advise of their manager, his time with the Band was finished. Robbie Robertson still collects royalties from all the songs.