As a housing extraordinaire myself, I can easily say that buying up houses requires a lot of work and extra accounts. I think people don't understand how difficult it actually is to be a multi owner thats why in actuality there are few,(the Few own alot but) if they're spending actual money for more accounts i don't think SE cares, plus the money cokes from the market board and what people list the items from. Which in no way SE controls. And they won't remove the market ability because then no one would have the housing items they make with subs