Food choice being a proxy and signal for class/culture is nothing new. You’d be hard pressed to find a cultural tradition that doesn’t speak to it.
While everyone needs sustenance, there are often several adequate choices about how to get it and making those choices become a way of communicating to others. And communicating is an defining and seemingly valuable part of being human.
It’s not really weird and it’s not going anywhere.
I share the same concerns about quinoa as OP. My guess is that it has to be made and served fresh, and these stores have it sitting on shelves for days at a time and it tastes funny after a while.
While everyone needs sustenance, there are often several adequate choices about how to get it and making those choices become a way of communicating to others. And communicating is an defining and seemingly valuable part of being human.
It’s not really weird and it’s not going anywhere.