The rent freeze is his policy, but that's distinct from rent stabilization.
In my opinion its a distinction without difference.
Whether it is a "rent freeze" or "rent stabilization", it is all doing the same thing... telling landlords "We are artificially going to put limits on the profits you can make". And when you do that, you will cause at least some of them to decide "You know, I can earn more profit by turning my land into a parking lot, and I won't have to deal with all sorts of tenant-related headaches."
Now, I am sure that there are lots of far-left folks who will say "good riddance". But whether you think those landlords are greedy capitalist pigs or honest businessmen scraping by, the fact is they were offering something that was needed. And now there will be less of what is needed.
There was lots of evidence to support a rent freeze this year. Despite all the handwringing about landlords not being able to afford basic repairs, landlords saw a 12% year-over-year increase in net operating income.
The problem with that particular metric... it is an average. Not all units had the same increase, and it likely depends on the neighborhood, if there is a mix of rent-controlled and non-rent controlled units, etc. There are also other issues: that 12% may not be adjusted for inflation, that "increase" covers maintenance that have also been increasing, etc.
(also, I am not sure where you got your 12% figure from... nationwide or just NY, all rental units or just rent-controlled, but it differs from values that I have seen.)
From:
https://finance.yahoo.com/economy/policy/articles/nyc-landlords-report-6-2-164654085.html
For the third consecutive year, the financial health of rent-stabilized housing in New York City appears to be on the up—at least on paper. Net Operating Income (NOI)...for buildings containing stabilized units climbed 6.2% citywide in 2024,... But in the Bronx, NOI dipped by 0.1%, with some neighborhoods like Hunts Point seeing a staggering 13.1% collapse... even though net operating income is up overall, growth is thinnest among buildings that are entirely rent-stabilized units, at just 2.2%. The report also shows that expenses are growing fast—up 4.2% since 2023... Inflation is also eating into incomes. Citywide NOI growth drops from 6.2% to just 2.2% when adjusting for inflation, Taxes represent one of the biggest drivers, accounting for 26.3% of all costs. It's a significant finding, given that there are at least two proposals currently being shopped by the Mamdani administration that would raise taxes for property owners... ... the city's so-called "ghost apartments"—an estimated 50,000 rent-stabilized units sitting vacant because the cost of rehabilitation far exceeds the potential return...
Notice that? thousands of units that are sitting empty because the landlords figure they won't earn enough back to make fixing them up worth while. And that's with various increases in operating income over the years. Now there is a rent freeze, and even more buildings will fall into the same category.
Tenants, meanwhile, saw an overall drop in income.
I am sure lots of tenants did see a drop in their income.
Yes housing affordability is a problem. Yes, lots of low and middle income people have seen stagnant wages while other expenses go up. But when you go and deliberately make one group (the landlords) largely responsible for "fixing" the issue, you will have side effects.
I'd say say Mamdani has a very firm grip on the fundamental problem here , which is that we just don't have enough housing in NYC.
That is... debatable that he has a "firm grip" on the problem. There is plenty of evidence that rent controls contribute to housing shortages, and a rent freeze is an extreme version of that. That rent control reduces housing availability is an idea that many left and right wing economists accept. Mamdani is doing something that the majority of economists say is wrong. That doesn't sound like he has a "firm grip" on the problem, it sounds more like he is taking the populist approach. "I'll do what sounds good rather than what the experts say"
He's very gung-ho about incentivizing developers to build more.
Actually I would say he is doing just the opposite. A rent freeze the reverse "incentivizing developers to build more". Instead, he is telling them "I am willing to limit your profits if you build housing." They would be better off to use their resources to do other things if they want to maximize their investment.... stick money in the stock markets, build retail instead of residential, develop a death ray in order to blackmail the world, etc.
Now, he may have some other ideas to create more housing. But rental units constructed and run by private individuals and companies will always be a major factor in the housing market.