this feels like it leads to massive corporations still owning all of them and paying large taxes

Then the taxes aren't high enough. That's an easy fix. It's one of those times the state doesn't want to optimise the rate for total tax earned but to make paying it for any length of time actually prohibitive. Make it so that they can't possibly raise rents high enough to cover those taxes and they'll understand quickly.

The other side of the equation is a bit harder, and that's housing overstock: Companies will be sitting on housing they can't rent out due to lack of demand for housing. One idea would be to allow them to lease homes out to municipalities for literally nothing but tax forgiveness and the municipalities can use that to house the left-over homeless, unemployed, etc. Call it a half write off. Oh those leases need sensible minimum durations, I'd say five years is a good start.

smaller investors that used property for assets

You can easily make smaller investors be hit significant less by it by scaling the tax to the number of vacant housing units. Own a second home you rent out and spend four months finding a renter you like? Fine, pay ten bucks. Do that to 1000 housing units? Pay 10000 bucks for each.

Yes, those kinds of rates are right-out financial violence. That's the point: The state has to step in as the larger bully to keep the small ones in check to avert market failure.