Why are Americans obsessed with hearing opinions they already believe expressed poorly by children? Its all very cultish and creepy. This is something The Simpsons used to make fun of back when it was relevant.
This is a fine example of a kid who has a strong opinion and, rather than shout it into their echo chamber on social media, they've taken the liberty of securing a domain name and creating a website capable of reaching a larger audience.
We here on Hacker News enjoy celebrating the initiative, the creative process, and the execution. Of course you'll find a wide range of opinions, but I think you'll find (and you imply as much by your question!) that most people on HN are happy to celebrate a the accomplishments of the next generation.
https://m.youtube.com/watch?v=gF6d0ROiFVg
Not to mention Greta and her fawning coverage in the American press.