The most irritating thing is hosting a game and having to boot novices constantly in order to have at least a semi-skilled player game. Other players get frustrated and leave if it takes too long. There's often server errors if you don't boot them correctly (let the game fill up then boot and replenish slots)
Can SMG make it so that a player has to request to join a game before actually entering the game? A screen of players requesting to the join the game can pop up and the host can accept or deny the ones in the list. The player would see "asking for host to join" for 15-30 seconds and auto abort if no response is made.
I realize this could be annoying for the joiner if nobody wants them to join. So it's still ideal if you can create a minimum and max rank / point value when creating a game, so that only those types of players can join and only those types of players can see the game. it should definitely be one of the filters too. "rating" for the playing skill of the game.