Lots of landlords are stupid and will raise rent beyond the market clearing rate just to make a quick buck, resulting in empty units and shitty communities.
Most economists believe that a ceiling on rents reduces the quality and quantity of housing available.[41][42] This view is based on analysis of empirical evidence as well as the understanding generated by theoretical models.[42] Economists from differing sides of the political spectrum, such as Paul Krugman[43] and Thomas Sowell,[44] have criticized rent regulation as poor economics which, despite its good intentions, leads to the creation of less housing, raises prices, and increases urban blight.
Now that I think about it further, it seems obvious that rent control would be a tool that can be used by a municipality to control rents in either direction, depending on their goals.