landlords should prioritize filling units. if they insist on squeezing people for rent while leaving inventory unfilled, they should be squeezed by regulations.
Theoretically that works for current landlords - what happens in a year or two when there are now no new rentals on the market because there are no new landlords because who would take that deal?
Isn't this what Vancouver did, by levying additional taxes on vacant units? (In that case, for absent buyers parking money, but same effect)