> If you’re paying 6%/year in property taxes, a home is no longer an “investment”, and the house hoarding (especially by the likes of investors buying single-family housing) will cease.
It wouldn't accomplish that. The big investors would just shrug, keep buying houses and renting them out, passing your 6% to the renter to pay. Meanwhile regular people would be priced out of their home by taxes, reducing home ownership even further and those big investors would snap up those homes. Repeat cycle until those corporations own 100% of all properties.
You want to incentivize owning and living a home, so I would do 0% tax on primary residence (up to some value limit), maybe 5% on a second home and ratcheting steeply up from there on each additional property owned by a person or entity.
That would wipe out the corporations owning hundreds of homes since they would not be able to profitably rent them out if they're paying 100+% tax on each. Meanwhile regular people can live in the only home they own without tax.