Are you kidding? In the environment where I have grown up, most of adults - parents, relatives, teachers - openly despise and humiliate teens and don't even notice it, because everybody have accustomed to it. They judge and "psycho analyse" in the most humiliating ways at first opportunity.
As one of my relatives said, when I've asked them stop to insulting me (when I was a teen)... "Insult you? How one may insult a kid? Adults don't insult kids, they just educate them". When I've asked another relative to stop beat me up, they said "Beat you up?! Why do you say it, like I am a monster?! I'm not beating you, I'm teaching you!".
They don't give a shit about young people feeling ("feelings? It is just hormones/caprice/simulation"). They percept them as not-quite-human, and often pretend that kids can't have an opinion or feel pain, because it all is "not serious" anyway. Also some of them have inexplicable convintion, that kids and teens will forget all abuse, when they will grow up, which give them even more strong sense of impunity.
I still remember the most disgusting and humiliating "reviews" about my creative work. These things were told me by adults, when I was a teen or kid... 10, 15, 20 years ago, but I still remember the humiliation, so strong it was.
Some people say that if one still remembers all of that in their 28, this person is petty, spiteful and immature (I suppose, they are the same people who believe that you should forget everything bad from your childhood and youth to NOT being "spiteful"). Yes, you can say that, if you want. In that case, I'd better be spiteful than pretend that such a things don't happen, because it would be an ignorance.
In my opinion, when young people hesitate to show their work to older ones, they have all grounds for it.
Yes, it can be useful. But only with some conditions. Particularly, if you'll show it to people, who:
1. Are versed in art, at least, a bit;
2. Have enough consciousness to be respectful to younger (which is again, rare case).
Then yes, you can get the useful critique. But if you'll show your work to ignorant and arrogant adult (which is much more likely), you'll just being mocked and feel like a piece of shit, but will not extract any useful info from it.