To jump off of this I'm still uncertain as to why all bagels are supposed to be just like NYC bagels or they're unfit for human consumption; they didn't originate there, after all.
My SIL took me to a bagel shop on Columbia (I think) that had the BEST bagels. It was next to a bra store owned by a Jewish Lady. I know she is jewish b/c we went on a Jewish holiday and it was closed. Apparently, she is well known for her bra fitting and taking control of the girls.
I'm not sure they do have to be like NYC bagels, but they do need to be actual bagels - boiled then baked - and not just rolls with a hole in the middle. NYC tends to make them correctly, and they are very popular in NYC, with is very populated, so they have become synonymous with NYC.
But another reason is because, and this is another I think reasonable "ugh transplants!" gripe NYers have - our city's name is co-oped by so many! A bagel, or pizza, or hot dog or anything else needn't be just like NYC does it else where... but if a store or company calls it
a "NY bagel" or "NYC-style pizza", etc then yeah it better live up to that name. Otherwise just call it something else. And if you are from somewhere else and you are used to the pizza, or hot dogs or whatever from there, that were called "NYC style" don't come to NYC and say its wrong here in the city and this is not how a "NYC bagel" is supposed to taste!
I had a very frustrating conversation once. Apparently there is a chain of hotdog restaurants elsewhere in the country called Coney Island. So a person came to NYC and made a comment about wanting a Coney Island. Well to me, that sentence makes no sense whatsoever. Its like saying you want a Florida or you want a Wisconsin. Coney Island is a place, not a thing. Finally they explain - as if I'm the stupid one - they mean they want a hot dog. "Oh you want some Nathan's!" I replied finally understanding them. Oh my gosh they got so
frustrated - again like I was stupid - that no they wanted an authentic NYC Coney Island hot dog. "Right, a Nathan's." We eventually had to just stop having the conversation.
I don't care what exists elsewhere in the country, but in
NYC Coney Island is a neighborhood, and the famous hot dog place there is Nathan's. Don't come here and tell a NYer they are wrong about that as if we don't know our own city. Its fine, and even kind of cool that elsewhere "Coney Island" is a word like "McDonalds" but that definition does not work here
People who come here ready to experience actual NYC are welcome and we don't have any hate towards them, tourist or transplant. But if you come here and try to tell NYC that they are doing NYC wrong... no one's going to like you.
(Obviously all 'you" statements are general and not directed at anyone in particular.)