It's not a self-evident truth, at least to me.
However, most modern youth cultures are defined largely by their lack of culture. They are instead about passively escaping society. The top comment on the first video in the article is literally literally "I have no friends and I’m sitting alone in my room laughing hysterically at this video". There is increasingly nothing to understand. It is an entire generation being marginalized. But you can of course argue that many people always were.
Addition: Another example would be the relative failure of things that would be expressive like the "maker movement", platforms like SoundCloud and E-sports.
That doesn't seem right, even the "Smash Bros" community has a culture, hell people talk about the YouTube community all the time.
Also, soundcloud gave rise to Soundcloud rapper movement and more broadly has been important in the hip-hop community, I don't think it's a good example
My point with SoundCloud is that it is a mostly a commercial failure. If youth cultures today was more expressive it would be much more successful. So would make magazine or e-sport venues.
I don't deny that there are cultures on for example YouTube, more the idea that there is something more going on. That we don't understand "beauty blogging", but in the future it will lead to something exciting. No, (or at least mostly not) they will go on to become marketing managers at some company and/or continue to sell Chinese cosmetics. Cosmetics happened last century with people like Estée Lauder.
Asia is a bit of a different story, which I don't know enough about to really comment on. But in the West it is very much that young people have shitty deal and are making the best of it by doing things like playing video games and watching people they can identify with and are popular.
If you think about it a lot of the content is about fitting in, rather than standing out. Which would be the more traditional youth culture.