I play to win, and that is what is fun for me. Its never that much fun if I'm losing. We post win rates because we are proud of them and our achievements. We may seem "elitist" sometimes, but all of the good players that post in this thread didn't start out good at this game. We were all scrubs once. Hell a year ago I had about 5k games played and less than a 52% w/r.
For over 5k games, I was that guy that people hated; little to no patience, constantly making stupid mistakes, and not really caring b/c all I wanted was that tier 10. Then I got XVM, it opened my eyes, I saw people with 57%+ w/r, and with my goal of getting a tier 10 completed, I now turned my attention to improving.
Its like I flipped a switch at some point, and after that I have been constantly improving my gameplay and stats.
Believe it or not, most of us "elitist" will gladly advise people on how to improve. Hell, I stream almost all my games in hopes that people watch and learn, and I actively answer my viewers questions when they have them.
Do we bitch about our teams? Yes. Everyone does, regardless of win rate. Anyone who wants to win will get frustrated when half thier team goes and lemmings in the first 90 seconds. The forums just so happen to be a great place to vent that frustration from time to time.