When you talk to people from a major metropolitan area about culture outside of a major metropolitan area, they're very often not talking about culture. They're talking about entertainment, and a specific kind of it.
I live in semi-rural Michigan and the idea that there's no culture here is just kind of absurd. The culture just doesn't consist of having a constant stream of touring musicians and restaurants for you to spend money on.
Agglomeration effects are real and there are centers of dance and music around the country that exist in self-reinforcing cycles of training and performance. These scenes come and go but they don't arise by themselves in isolated dying towns.
Some styles of dance and music, which are a component of an overall culture, are totally centered in large cities. Music is a bizarre thing to bring up -- bumfuck nowhere Midwest smalltown is the origin and inspiration for plenty of music that is listened to well outside of the geographical region it's from. Hardcore punk has plenty of representation from gutted Rust Belt locales, and Midwest emo is straight-up named after it. They do arise and perpetuate themselves in isolated locations, all around the world.
Of course there are cultural aspects that large cities will have and more rural areas won't, as well as the other way around. Neither are lacking culture by virtue of lacking the other's culture.
More different kinds of culture (diversity), more examples of each kind (quantity), and usually better examples of any cultural component which is available in both (quality).
Rural areas certainly have cultures of their own. It is not binary.
But you cannot reasonably compare the cultural opportunities of urban vs rural and assert that rural is not lacking, unless you are thinking of your personal preferences only, and the rural area you're using for comparison happens to match up very well with your own preferences.