A landlord cannot absorb the costs of major repairs if he can't raise rents, nor any other rising costs. Remember, the cost of living rises for the landlord as well as the tenant, and the landlord has the increased burden of having to take care of his property, pay taxes, etc. He has to be able to build those costs into his rent or he is losing money, and losing money is not why he bought property to begin with. Property ownership is a business. If it is unprofitable the landlord will cut his loses and dump it.
What that means is a lot of properties will start declining as maintenance is deferred and the landlord will prefer an empty building to tenants who don't pay. He'll try to sell if he can, and who is going to buy? You get into a downward spiral, with properties decaying and sub-par tenants coming in under government funded programs which guarantee the rent is paid but do not guarantee the quality of the tenants. Or the building empties out and sits vacant - a playground for criminals and scumbags.
I've seen it happen many times when I worked in real estate.
Raising rents is one of the prime tools used to control the quality of your tenants. Without that you have to accept people who may tear the place up or ruin the neighborhood since you can't discriminate based on anything other than what is on paper; if someone has the money they can get the property. High rents is how you keep out the riff-raff.
Now it's impossible and New York is going to go into decline. Mark my words.
If you put your thumb on the scale the other side moves. It's how it works in real estate. Freeze rent by law and you wind up with a declining market. It's as simple as that.
By the time Momdani is done New York is going to look like it did in the Kurt Russell movie Escape from New York. They'll have to put a wall around it to keep people in.