You could not be further from the truth. I've had, and been victim of, many majestic comebacks.
The other day Flames were down the entire match and it was 200-700-700, and Flames took that 200 and through a series of really good luck with node spawns and a fantastic strike team, turned that 200 into 800 and won. Sure it sucks that I lost, but it's not like I didn't go down without a fight. I never do.
Often times I see many people just start to give up when another team is close to winning. The defeatist attitude is the thing that defeats you. You can't give up, there's many ways to turn matches around.