The current way Bungie is dealing with AFKers isn’t really stopping people from AFKing in matchmaking. The problem is the current method is too reactive and by the time the players are banned, they’ve already ruined a lot of peoples games. Not only that but it reduces Reach’s overall population even further. These two simple changes could easily reduce the number of players that AFK in matchmaking while not reducing the overall population.
Automatically send player/party back to lobby. Back in Halo 3, you always returned to the lobby and had to manually start the search. That prevented players from AFKing in back-to-back games as they had to start up the search and the end of every match. With this added to Reach, it would atleast stop those who went AFK in the previous game from searching until they got back.
Remove Game Completion credits. This is one of the biggest flaws with the credit system. Because it gives the most credits per game (not including completing challenges or commendations) and you get it regardless of winning or losing, it promotes people to AFK. This is most apparent in Firefight where you are almost guaranteed 1,500-2,000 credits from game completion. If Game Completion was removed as a source of credits, then players who purposefully AFK wouldn’t have a reason to AFK as they no longer would be rewarded for not playing.
Of course with the removal of Game Completion as a source of credits, the amount of credits a player could earn would be severally decreased. To compensate for this, I’d propose that Winning become the primary source of credits. This would not only make players actually play to level up, but it would give a good incentive to actually win.