Again, that is inherently a policy decision that reduces density and affordability; by definition, "landlords" are people that own and operate multi-family dwellings. You could just as easily ask "why not give more of a preference to landlords?"

It's probably useful for you to understand my, uh, priors? about this, which include the fact that I live in an overwhelmingly SFZ community that actively works to prevent the construction of multi-family dwellings, often with appeals to the evil of "landlords".