This forces landlords to do two things:
* When there is a sustained rise in fair market rent, they will need to implement that increase over time instead of falling behind, and then raising it all at once 5 years later when they realize they're leaving 20% on the table. This allows people being priced out advance warning.
* When there is a spike in fair market rent, like the 8-10% spikes of '14-'15 in the Bay, they will need to spread that rise over multiple years. Since this doesn't affect the profits of new units brought onto the market in response to the demand spike, it should have minimal if any effect on supplier behavior.
(And what happens when market clearing price does increase at 5%+inflation for years on end? Then housing will come to dominate the CPI, and the "inflation" term will more and more closely track housing prices.)