I don't know if people just don't understand what surrendering is, or if they spitefully refuse to do it, but I've never seen someone surrender.
I played a 3v3 today, Gateway. I got attacked on one of my colonies, and quickly brought my fleet back as I churned out more ships. After driving him away, and following him every step, he quit. Fine, he only had 3 planets, and I had business to attend elsewhere. Next, I put the killing blow on another guy after they finished off one of my teammates, who quit too, not surrendering. I asked him to surrender. Not quit. Surrender, twice. What does he do? Quit. I spend the next 30 minutes getting ready and then killing the remaining guy. I asked him to surrender....You guess it, he quit. Now, this leaves me with roughly 13 colonies that I needed to kill. Luckily, after my last teammate had retreated losing his homeworld, and everything else, he rebuilt and managed to help after he got his feet under him.
This is an unnecessary another 30 minutes that I need to waste. I love this game, but when this happens, it's just frustrating. Am I to assume that in the next patch, with the AI in multiplayer games improved, they'll surrender, saving me the time?
Also, if all members of a team quit, but another team still remains after 3 minutes, it should be a victory for the remaining team, I think.