It would require a lot of housing density for everyone to own four dwellings (and would kill rent demand well and good), but I wouldn't call it infeasible. For everyone to have a quarter acre lawn and a 2,000 square foot house that shares no walls with neighbors? With those additional requirements having everyone own four is infeasible, sure, but a belief that's the only dwelling worth owning is how we have throttled our housing supply in the first place.