That’s the problem though because there is a meaningful distinction to be made between landlords renting out surplus space in their primary dwelling, and landlords who own dozens or more of properties which they rent out. Based on context I assume they were using the word landlord to exclusively refer to the latter, even though both groups would generally be called “landlords”.
As I imagine it, the person who rents out a single apartment for subsistence cannot pull all kinds of tricks that a large landlord with multiple properties will. They don't make the market, merely participate in one.
Moreover, a large landlord will often siphon the income into paying off more apartments for rent, taking them from market. Whereas for these single apartment landlords may consider selling their propertied instead of renting out so they don't hoard the stock as much. Their income from renting out is insufficient to buy more reliably.
That’s the problem though because there is a meaningful distinction to be made between landlords renting out surplus space in their primary dwelling, and landlords who own dozens or more of properties which they rent out. Based on context I assume they were using the word landlord to exclusively refer to the latter, even though both groups would generally be called “landlords”.