Yep, as everyone knows, California invented beaches. There were no "beach kids" before California, and everyone who grows up elsewhere on any coast is emulating southern California.
Which is a style replicated, distinctly with the californian beach in mind, in other locales
Obviously not because californian beaches were the pinnacle of beaches, but because the media treated it as such, and entered a positive feedback loop to entrench its (current) position there
In the same way, the East Coast has beaches are associated with yuppies and yatchs, and the hawaiins with hawaiins and tourists
Its an image ingrained within the American conciousness; regardless of whatever "true" merit it might have, the descriptive language is universal (to all who consume american media, and media deriving from it).
I am going to guess you haven't spent a lot of time in New Jersey.
At best, it covers the majority of the relevant space, for the relevant time.
At worst, it's a hyperexaggerated representation of reality, possibly one that is hoped to exist (but does not), from a minor section of the world applied to a much, much larger area.
But neither I nor this article (and marketing in general, as does much of the arts) does not speak of reality. This is a discussion of the image, shared between most of the country. (Reality itself is only shared between those happen to percieve it, and that is rarely more than a very minor subset of the population that has access to the image)
Thus: it isn't relevant what New Jersey is really like. It is how New Jersey is perceived that matters. (Which I may still be wrong about; I can't say I know much about people's image of NJ).
The yuppies and yachts mostly come from NY and elsewhere ;)