The economists voted on what works, the party leaders on what feels good.
Like any price control, a rent cap crops supply. Investors aren’t stupid. They will not build rent-controlled housing if they can obtain a higher return doing something else. Landlords aren’t stupid either. If renting becomes less profitable, some of them will sell their units, as condominiums, to the well-heeled.
Other landlords will offset their loss of revenue by spending less on maintenance. The quality of housing will deteriorate, and a bureaucracy will be needed to police the increasingly bitter relationship between landlords and tenants.