Sorry to jump into the convo later, but there is no way the quitting and griefing was this bad back in halo 2 or Halo 3. It was probably the worst in Reach, where I think the saturation of shithead kids with consoles just converged on the game. Even Halo 4 launch was bad, I still remember launch week, people just betraying you and destroying your tank on exile, all kinds of stupid stuff.
I think the fact there has been very little consequences the past decade, you've allowed this shitty behavior to be cemented. People need their instant gratification, scared to lose or scared to play ranked playlists, used to just quitting without punishment, thinking that they can just team shoot and nothing happens etc.
Don't get me wrong, it's always been there, but I feel it wasn't as bad back in the day. Maybe that's just my memory though.