If there is truly no housing vacancy, nobody will pay the vacancy tax, and NIMBYs have weakened their position by losing an excuse to block housing construction.
If there are a large number of warehoused homes, and a vacancy tax successfully puts those homes on the market, then housing prices go down, and if they’re still high, the argument for building more homes is even stronger. You will have a bunch of progressives who have seen with their own eyes that increasing supply lowers prices.
This confusing ideological misalignment also happened with AirBnB regulations. YIMBYs, in general, were against it, but the week that San Francisco’s law regulating AirBnB went into effect, a flood of new apartments showed up on Craigslist, nudging the overall price for new apartments down a few percentage points.
Either you believe in supply and demand, or you don’t. We need new housing construction, and we also need to make it extraordinarily expensive to keep homes intentionally empty in cities with low vacancy rates.