However, there's an issue with how you're calculating the market rate: You're assuming that tenants can/will bear that cost indefinitely, so the market rate can be "whatever the landlords want to make it". That won't always be true, not just from landlord defectors who might try to undercut the oligopoly on price, but because the tenants can move elsewhere and effectively remove demand.
Well, “Nothing” is an unusual way of referring to the Sherman Anti-Trust Act.
To undercut that this year would mean being below market price in a future year. The only arbitrage would be between present and future prices. Perhaps some subset of landlords only seek to rent out for the front-end years, so they would have a different calculus, but all that would do is to pull down the average transaction price by a little, according to their size in the market. So if the current price demands a natural increase of 2%, maybe the market will clear at 5% instead of the 7% max, but it remains the case that there will necessarily be years where the clearing price is higher than without rent control.
[1] This is assuming the government "guesses" it right that 7% is the average rate of increase over the long term. If it is below average, then the market gets severely distorted.
And the cap was explicitly set to be below the average rates of increase for many areas because the effects of the higher increases in those areas is what the law is explicitly trying to prevent.
Spreading the increase to a leaner year only works if the unit is below the market rate. If the unit is already within 7% or so of market rate, then market won't bear that increase. Instead the tenant will move out to a market rate unit. If the entire city increases in lockstep that means people near the bottom of the market will be literally priced out and either move to another city or resort to sleeping in their cars or become homeless, but everyone else will just downgrade the size of the unit they rent since once the price of the current unit exceeds their ability to pay. At the very top end of the market that will mean units will have decreasing occupancy rates assuming the landlord refuses to compete on price to increase demand and insists on capturing the 7% increase.
You are forgetting about transaction costs.
The new law does provide a Schelling point. (But I do agree that it's probably not going to be an important one.)
