https://en.m.wikipedia.org/wiki/List_of_NFL_players_by_games_played
This is most games played, four QBs are from this era, Farve, Manning, Brady and Brees. After that is Tarkenton of all people who I believe played 14 game seasons. Next are Marino and Elway. I think that the fact that four are from an era where the rules are designed to protect the QB has to be considered. Farve was an animal, he had nineteen injuries and played through eighteen of them. I know at least early in his career he had some pharmaceutical help. Brady by comparison has had five played through four.
I agree with you that conditioning, lifestyle, probably medical care have a good deal to do with longevity.
By the way I once caught a pass from Tarkenton.