What your link is getting at is if you increase the tax on property/land value, it instantaneously reduces property values to account for the net present value of the future tax payments. So passing it is one-time very bad for current property owners.

Because the housing market is extremely efficient. Rents are essentially property value * current interest rate + taxes + property maintenance costs. But rents are also set from the other side by what renters can afford to pay. So if you increase the tax, the property value goes down to compensate. Anyone who buys the property after the tax is already in place is unaffected.

So there are two ways of looking at it. One is the renter pays the tax (i.e. the formula for rent has "the entire amount of taxes on the property" as a component) and the other is the tax is paid entirely by whoever owned the property when the tax was enacted, via a large reduction in property value. It depends which point in time you're looking at it, the moment when the tax is enacted or rent paid by tenants in the future as a percentage of then-present property values.

But in any case the tax isn't paid by speculators who didn't already own the property in year zero of the tax being enacted.