I think it's natural for older people to react with dismay when confronted with a younger person's pessimism about the future, but to say that it is failure of obligation or responsibility is seriously misunderstanding, even willfully, the kids thoughts on this. The situation is, in fact, quite reversed! Consider a child who is more pessimistic about the future than their parent at the same age, why is that? You could hand-wave it away, as people tend to do here, and say its a problem of education, or they have been brainwashed, but no one seems to consider just how much intellectual autonomy or rationality you are denying the kid to have, you are choosing to simply deny flat out any basis for the kids pessimism.
You could also conclude that, in fact, the world is worse for the kid then it was for the parent, which I believe is occams razor here, and what else is that but the failure of the generations before? You can blame the apps, but you made the apps (quite literally around here); you could blame the schools, but who was responsible for the character of education in a country but the voting generations of the past? But instead, everyone would rather just doubt children, or say they are lazy!
We inherit the world we are born into, yes, but there is no sense or ground to the world, it is flying blind. Older people are saddened by deep pessimism of younger people, because deep down, it is nothing more than an indictment of the world they have left the kids, and it hurts to reckon with that, so this thought rarely passes into consciousness, happy to be deflected onto presumptions about the kid's responsibility.
It's sad to not have a shared future between generations, but like in the article, we need to take seriously the irreality of the Future. At the end of the day, kids do not like your future, the future you have left for them. The trajectory of the world as it stands.
To me, it is heartening that kids, maybe not yet with a sense of agency, manifest profound pessimism, because it is correctly identifying a problem in the grandest, most existential sense: the narrative of history we have been operating on for a long time. Profound pessimism is a seed that can grow into powerful critiques about the most unsaid and damaging assumptions of our time.
If you are so angry that kids would dare question the longevity of the world they find themselves in, you are saying something more about yourself. You take it personally, because deep down you know they have inherited, in part, your own failures.