Ehh...I'm not Beatles fan, but I wouldn't go that far. I know a lot of pit players and jazz guys that moonlight in rock, funk and R&B outfits for the fun they don't have in some of the stricter formats. I think what happens is that many players fall in love with jazz when they start getting into it and constantly push to reach the next level. It doesn't really leave time for the other stuff...it becomes an addiction. That said, one guitarist I play with sometimes works part of the year on a cruise ship playing in two different bands, one covering the great American songbook and the other basically a dance/party band. When he gets home, it's all about the jazz...he has zero interest in just about any other style. Also, it's worth noting that most hobby players worth their salt can get out and play as much rock and R&B as they want but the musicianship bar is set a little higher with jazz, meaning they really need to have a thorough understanding of harmony and rhythms that aren't quite as prevalent elsewhere.
Then you have guys like Tony Levin who has rocked harder than most people can ever dream of, releasing a jazz album playing cello! I don't think it's as black and white as "jazz guys are snobs" or "rock guys are unskilled musicians", etc...