I'm starting to think he might be right. I just got Red Dead a few days ago and I've only spent half my time actually doing missions. I've helped half a dozen strangers, hunted and picked flowers, took a ride on a train, attacked a gang hangout, and just rode my horse around the world.
And when I do go for missions they feel so much more personal than literal Grand Theft Auto games, there you feel like a hired (or in many cases threatened) gun most of the time, in Red Dead you feel like you're helping friends. I think part of it is that you're not running around killing civilians in this game, it really affects how it plays out.