Of course it feels terrible to play a lost game. I would just leave as well. However, I think players can "abuse" this mindset. People leave after losing the first engagement, losing vp, fuel, etc. I seen players leave for the smallest of things. I think there's a fine line between leaving because there is no more hope, and fighting it out
There is option to vote for team surrender in case you don't want to continue to "play lost game".
At least it is honest to other players of your team.