More wards is something SE would do if they found it easy, but it means running a new server program and the space and resource requirements that come with that.

Because "subventions" would work just like apartments, that idea is possible but you could argue it already exists because when you enter the house, there are rooms that multiple people can have a version of. The difference with your version is the rest of the interior of the house would have a separate version for each person. The problem is that only one person could own the garden.