If you are really concerned with blight, “abate” itIn New York City, that means that the Department of Buildings and other agencies should enforce code violations.
There is another tool which government has to control “blight.” It doesn’t cost nearly as much as purchasing the land and so far as I understand, it can be very very effective. It’s called abatement. There is little doubt that a local government can use abatement if it wants to.
Of course the standard for forcing someone to abate the nuisance they are creating requires some real facts and not merely hand-waving claims. So it is not as useful for institutions and organizations which wish to get land cheap or without having to bother with capitalism.
However, the Empire State Development Corporation punted when asked what agency was responsible for the upkeep of the grounds around the Vanderbilt Yard.
Obviously, you can't abate the "blight" of a working railyard via code enforcement. But neither a rezoning nor a request for proposals was proposed to remove that "blight."