they broke up in 69..they decided to stop being a touring boy band in 64. Started doing studio records in 65 with Rubber Soul and Revolver and hit their peak in 67 with Sgt Peppers.

Because their contract was structured like Elvis's with a movie/album deal..The record company didn't want to put any money into their productions, they just wanted something cheap and fast to churn out. So everything they did was through being creative. Acts like Hendrix had access to a lot better equipment. In fact Abbey Road, their last album, was the first album they recorded with an 8 track recorder instead of 4 track and was their first album released in stereo.