I think once someone is rage quitting, they've pretty much left all reason behind. And that applies to everything, really. Rage quitting a sub-par group? You'll probably spend longer waiting for a new party than it would have taken to complete the instance with the old one. Rage quitting a losing battleground? Enjoy your deserter debuff--you would have gained more efficient honor by staying. Worst case scenario, you suffered through a few more minutes until you could enter a new one.
Really, there are only 3 times when it is worth quitting a group that I can see.
1. You care about the loot, and are in the group with a ninja you can't get rid of. Which usually means its the leader or their friend.
2. You don't like the people you are playing with to the point where it's actually taking away from your enjoyment of the game. I don't have the profanity filter turned on, in part because I don't mind seeing minor curses (no children watching me play either), and partly because the filter blocks some really idiotic things. But if they are using really gross language, or talking about something I really don't want to be a part of, I'll weigh my options between /ignoring them, leaving, or both.
3. The people are so bad that you are sure you can find a new group faster, or doubt the group's ability to finish the instance anyway. This often involves idiots wiping the group because they run ahead of the tank, tanks that refuse to watch healer resources/oom calls, dps that pull 6 new groups and break CC, etc. Generally speaking, it's probably going to include multiple issues.
None of these apply to warzones. And, afaik, there's no where to see your win/loss ratio in game.
It'll be close, but Romney has the momentum.