this was a very weirdly written article, but the gist was actually many people not realising that the property records in the USA are publically available. As in, there's literally a website for most cities in the USA with a list of homeowners and addresses, because titles are publically available info over there.
ANYONE can hop onto the title records and do a lookup in the US. (I live in Australia, where this search is generally restricted to licensed professionals e.g mortgage brokers who are bound by professional codes and will probably get their license stripped if they, for example, used their access to Titles/Land Registry/Landgate to stalk their ex or whatever).
As part of the pied a terre tax, NYC published a "public assessment list" which was how a whole bunch of people who aren't necessarily even on that list (or are on there by mistake, e.g they don't actually own another property, they just sold one somewhere else and the records didn't update or whatever) just found out that their home address is public info and always was.
Funnily enough, it's only not public info if you already knew that and you formed a holding company to buy your own home for you, as per this essay ("A quick digression for privacy minded buyers"). The rich and famous have always known this, so they have always had their homes sitting in a trust so their actual names aren't on the public records.
As usual, this mainly affects the people just rich enough to have a mortgage, but not in the kind of circles where this fact is common knowledge. And for quite a lot of people, a mortgage is basically just rent you pay to the bank instead of a landlord (particularly if you can only afford the interest).