If you live next to an empty lot, and the local government allows an apartment complex to be built on it, your house just dropped tremendously in value, both due to loss of privacy and the large boost in supply of housing, which was previously lower and inflating the price of your home.
I don't think they were saying it benefits every private property owner. It's clear that there is at least one private party that benefits from the ownership of that apartment building.
How does that benefit you?