Maybe just outlaw the ownership of more than 3 houses? Landlords will throw a fit but they're a minority and I think they're doing fine if they have 3+ houses.
Even if you think the perpetuation of capital unfair the realities need to be acknowledged in order to even begin to think of a viable alternative.
I lived in houses rented by these part-timers and they were pretty haphazardly managed compared to the [fewer] times I lived in clearly corporate-owned and managed properties.