I don’t think this is as much of a slam dunk as you think it is: keeping properties empty is a timeless tradition among NY realtors, and applies equally to commercial and uncontrolled residential properties as well. You just don’t hear about it because they aren’t tracked.

Real estate, as far as markets go, is exceptionally prone to profiteering via reduced supply. It’s unlikely that these 60k units would be unprofitable for their owners; the owners have simply determined that they’re not profitable enough.