There's not much Blizzard can do on the end of consoles for banning. Top 500 on each console is filled with KBM (Keyboard and Mouse) DPS players for example and that is also a bannable offense. However its been the same people using it for over a year and no actions have been taken. When Sony and Microsoft give these simple options where 1 game can be owned on a console and over about 10 accounts can have access to this game, it just allows anyone essentially to have a smurf. There is really no way to stop it, but I'd reccomend that if you get matched with them in competitive then just mute them and keep playing your best and trying to win. People often forget about the mute button and it is a key part to staying untilted in games.