I think the most novel proposal we put forward in the report is taxing the total real estate holdings of large landowners, as opposed to individually taxing each property using the aforementioned brackets. This could entail situations where large landowners own a portfolio of properties, each falling below that $3 million threshold, but that cumulatively add up to tens of millions of dollars. In this scenario, by taxing the total holdings instead of each property separately, these owners would no longer be able to avoid paying those progressive property tax rates.

There's a few interesting bits to this article, but I like this one the most. Property taxes on the cumulative amount of property a person or company owns is huge. It provides a punishment for buying up large amounts of property.