I think it has become a bit line brew where people thought American versions were bad until they started to dig into it more and the craft scene started to take off. Similar with pizza. You have regional styles that no one really wrote about but in more modern times people are looking under more rocks. Locals always loved it hence why d sad one of these joints have been open so long. And a craft scene around those styles grows from it.

In short the upper middle class got tired ordering Pizza Hut and has co-opted the working class styles (New Haven, Detroit, tavern style, etc).