Probably because New York doesn't have a style of pizza. They have pizza.... That New Yorkers (for some reason) thinks is better than it is elsewhere despite it literally being no different.

Take it from someone who did six years as a line cook, 2.5 of them in a high end pizzeria called Pizzeria Gusto. I'm probably about to get flamed, but that is the honest to god truth.

(yes I've been to NYC and yes I tried multiple pizza joints recommended by my local friend.)

What most people call "new york pizza", or, the impression that I got when I was there, was that New York pizza is the same greasy (delicious) crap that it is in any "fast food" pizza joint anywhere else. And don't get me wrong, you can get some damn good pizza in NYC, but, seriously... Go to any big city in North America and you'll find the same thing.