I think you might be reading the post differently from the people downvoting it.
Why would punitively taxing vacation homes, which are almost always outside of urban / dense-surban locations where there is little housing market congestion and where building additional housing units is straight forward -- do anything to help things?
Why would punitively taxing the "ultra-luxury housing supply" do anything substantial for the issue being discussed?
To me, these points made the post sound like a class-war rallying cry rather than an effort at reasonable solutions.
Punitively taxing housing used by the wealthy isn't going to address the issue-- even if its successful at driving them out of the area there are so few that it wont make a dent in the market.
I'm disappointed in the lack of creativity in the proposals people advance. How about in regions where density is already over some threshold large employers should be required to have at least some threshold of their role qualified office workers working remotely? Remote workers can consume less square footage (less office space, less parking) and can locate themselves outside of the highest demand locations.
Surely there must be other alternatives other than just the density treadmill. While increasing density can also be a useful tool, it has the unfortunate effect of making the property even more valuable which works counter to the goal of affordability.
In California we should end the prop 13 windfall for rental properties, and at the very least allow rental properties taxes to rise with rental rates. Current policy can create weird effects like houses where if they were sold the increase in taxes would be comparable to the current rent, which essentially locks them into being rental... and even when it's not that extreme it creates a significant advantage in favor of long-time landlords vs recent buyers.