I mean, someone should get banned from cheating. I can see why this happen though, since the account playing does not own the game the account which has the game linked gets banned instead. If the account cheating has the game they are instead playing on their copy and that gets banned instead (i assume).
However the ban should be linked to the account and not the copy of the game. I do not understand why this isnt the case. Maybe because someone could just make a new account and link that to play on instead, therefor never having to buy more than one copy of the game while cheating.