Sure in the short term if you banned landlords today then the housing stock wouldn't really change. But you would see development drastically reduce.

Look at every market across the country where housing is ridiculously expensive and you will find a few common themes. 1st they have restrictive and burdensome regulations that make development difficult and more expensive, and 2nd they frequently have some kind of rent control. Restricting landlord's rights has always led to a shortage in housing as the incentives are no longer there for development.