A much easier solution, rather than going on a massive banning spree, would be to request SE to allow alts access to the person's main house. Then they could actually limit housing to one per account without upsetting people. And also, another terrible move by SE is introducing the moving feature so late, which has made people make alts, pseudo FCs and in extreme cases demolishing plots.
It is frustrating, but I see no point in blaming the players when they're not actually doing anything wrong in accordance with housing rules at the moment.
