At least for me right now it is rare the game in which every player playes the game untill the end. It didn´t use to be like this, the thing has started for me since Halo 4 came out to the MCC (I play on PC).
I tried restricting the game platform, game input and servers and it barely made any difference. I don´t know what has changed but it´s really annoying that people leaves most of the time. It´s not even a thing of being stomped and people quitting because of that, people just seem to randomly queue just to quit 1 minute into the match. Man, a match in this game doesn´t last that long, this is not cs go, you are not tied to a game for +45 minutes. Most games (Team Slayer is what I play mostly) last for 5-6 minutes, common. It´s not funny to have leavers on each team even if they are in the opposing team. You may end wasting 10 minutes in a 1 v 4 with no goal whatsoever.
I think something should be done about this. I suggest stopping people to autoqueue after ending a game so people should have to manually requeue if they want to play another game.
Also you could start making a matchmaking pool for people that often quit or go AFK so they start playing between each other only and let people who almost never leaves play with people alike.