Well technically Battlefield isn't an MMO , I used that as an example of a game which isn't an MMO which has more players in it and that is a First person shooter which relies on twitch reflexes .
Probably the best way to meet people in the game was these camps , the DutyFinder 15-25 min runs with players you never see again or even if you wanted to they are on another server is counter productive to trying to build a reputation as a good player.