Another unintended consequence is likely to be a degradation in the average quality of the housing stock. Everything gets old and needs to be replaced / upgrade

Another unintended consequence is likely to be a degradation in the average quality of the housing stock. Everything gets old and needs to be replaced / upgraded. With limited ability to pass on the cost of improvements, and less mobility for tenants, the best strategy for owners is to extract value from the property by neglecting repairs. The annual rent increase can be pegged at maximum, while the building itself moves "down market".