tl;dr: it is a deliberate consequence of the NYC tax code to encourage real estate development.
Because it's very clear that the middle class in NYC ends up paying for the lower middle class... while the richest people get away with laughable taxes.
Take the Hudson Yards redistricting example...
You mean Southwest Harlem.
https://www.bloomberg.com/news/articles/2019-04-12/the-visa-...
Are there unsold apartments? Then no because it means there are too many of those.
If you don't give Billionaires what they want they will just buy up the next best thing, like the apartment that you are currently renting.