Instead, "neighborhoods" are for the most part a geography defined by decades of shared knowledge. They are more "folklore" than science.
That said, the neighborhoods of Queens are real. Don't get into an argument about where a neighborhood ends or where it's headed. You will lose. We identify with our neighborhoods, much more than the borough of Queens.
So, then what's the fuss? New York City and the U.S. Post Office do not care what neighborhood you claim. All that matters is your zip code and street address.
Are all neighborhood boundaries then just "made up" or arbitrary? Yes and no. There are some geographic boundaries that define. For instance, Broad Channel is surrounded by water... Others follow major transportation routes or postal zones.
But plenty of other neighborhood boundaries are more defined by tradition and shared expectation than any other marker. That doesn't make them less real. It does make them susceptible to the whims of real estate agents.