I honestly don't have time for it. I play when I can squeeze in an hour or so to play, so any kind of organized group simply won't work. Plus, I found out years ago when playing MMOs that the way I want to play is not the way most groups want to play. I tend to be slow and methodical, virtually all groups are gung-ho and want to rush through the content. I'm the guy checking every box and looting every body and everyone else is running down the hall looking for something else to shoot. So any organized group or clan is out for me and there are far too many douchebags for pick-up play. Add to that, I'm not playing these games to be competitive, I'm playing to have a good time. I just don't have a good time playing with other people online.
Unfortunately, most games are built around MP, with single-player campaigns tacked on as an afterthought. There's this expectation that the only reason anyone buys the game is to play MP and SP missions are just training. Nope. That's all I want. I ignore the MP parts completely.
