It’s the death of channels like MTV and the emergence of the internet that specific subcultures are not defining the decades anymore. Subcultures still exist they just aren’t shown on mass media anymore since people live in their own bubble on the internet.

And if you think about it the reason why certain styles defined the decades of post war 20th century was capitalism. Certain sub cultures reached mainstream status because marketeers pushed it to the masses to make money. Like grunge or gangsta rap wouldn’t have reached the suburban teens if business men weren’t pushing it on mass media.