I only recall ever quitting one game since this game launched. The reason I quit was because I seriously had to take a dump. I held it as best I could, but it was going to be a nasty one, so I had to leave the game. I felt bad about it while sitting on the toilet, too. I don't think I will ever live it down. I just hope they pulled through without me.
Any other game It says I quit on I lagged out/power outage, and that is a rare occurence.