I work in the space, and while I can't conclusively state that it isn't, industry reports indicated a downturn in demand or increase in supply mostly towards the end of last year (via reduced occupancy percentages and average daily rate). Airbnb has been around for a while in NYC, and if anything, per news reports, I would expect their listings to actually be fewer or holding steady based on the local governments restrictions. Even if it was increased supply, there seems to be a more sudden drop in average daily rate in the past 6 to 9 months than before.

people who stay in $300+ rooms dont stay in airbnb just because its available.

airbnb rooms of comparable luxury are rarely cheaper than hotels.

Because airbnb has been around and haven't done anything recently that would cause such a dip.