Bungie cannot add matchmaking because - Player will join and stay idle all the time. Player will join and quit after finding few chests Player will join when atheon is almost destroyed Player will join and quit because the team has no 30s Player will join and quit when he see a lot low level players. Player will join and quit because he changed his mind. Player will join and quit after completing his "kill 10 vex majors or lords" bounty. or any other bounty.