The downside to shitting on landlords is that they will make sure that shit rolls onto tenants. Limiting security deposits to one month, for instance, has forced tenants with bad credit histories into shittier housing stock where the landlords have no choice but to accept lower credit scores. Before, they could put up two or three months of security so the landlord would look past their credit scores. (If you're asking why someone would have a shitty credit score but three months of security deposits, the answer is generally undocumented persons or persons working under the table.)

Making it harder to evict non-paying tenants will only exacerbate the effect. With only one month of security deposit and a one-year minimum for evictions, landlords will require stricter credit scores and income qualifications.