Well keep in mind not all people play for hours and hours on end. Some people only come in for a quick 30 minute game. For these people joining the winning team is just a way to have some fun. Not everyone takes it as serious as others. If I'm on a very limited amount of playing time I'm more likely to try to end up on the team doing the best so I can get the most out of the time I have. But if I'm going to sit out and play for 3-4 hours I'm likely to care less about which team I'm on as long as I'm having fun.