Its one of the few games where I honestly dont give a darn what my score looks like, just as long as my team is winning, and I'm doing something to help. If that means a well-placed dispenser as an engineer, or shutting down a couple doorways as demoman, or sitting back and healing as a medic when the entire opposing team is pyros on 2fort, I'm game with it. Thats why I like it. If I'm on, and have teh uber dominator skillz, well, I can do that. But when I see in the first few minutes that I'm just not all there mentally, I can find something else useful to do, like being the team spy checker on D.
No other game I've played allows you to do that. In dod, if you're off, you're screwed. I'd usually manage a 2:1 anyway, but its not fun.