I also remember reading somewhere that airsofters don't really get along with paintballers. I guess that was the case with me and my friend.
Paintball never really got me interested in it because of how the guns have huge CO2 tanks on the back and a tube barrel on top to hold the paintballs. It just doesn't look like a real gun. The whole reason what brought me into airsoft is how real the guns look and being a military/gun nut from a young age.
My friend was telling me though that they do have similar mil-sim type of games in paintball. I just don't see it as a true form of mil-sim when you're using paintball guns and wearing MotoX gear.