I agree. I play entirely solo so far, pretty much because I couldn't figure out posses early on (!) and now I'm used to it. I love roaming the West on my own, not knowing what is around the corner. I was chased by a posse of four players last night for no real reason, but it was fun, I gave as good as I got, and it was felt pretty authentic. I have a sharp suit, fancy weapons, I look like just the sort of dandy passing deadbeats might try to rob. Griefers wind me up in Elite Dangerous, but in RDR I don't mind them at all (and there realy aren't too many, in my experience). I meet plenty more friendly strangers. I patted another player's horse by mistake a couple of night ago, while he was walking to a post office, and he turned and I thought 'here we go', there was a pregnant pause and... he waved. I waved back and rode out. Later that same session I was defending some travellers, not doing great, another player arrived and helped out. When it was done, he looted a lot of the corpses, including some I had taken down, then he just turned and gave me a look, as if to say 'is this a problem?'. I thought it was fair enough, gave him a nod, and two minutes later we were squatting by the fire cooking some meat together.
This is the best game I have encountered for taking the rough with the smooth and thinking it all feels about right.
Sorry to waffle on.