Adolescence is the onset of adulthood before the capacity to function as a real adult in the real world is reached. One of the things that adolescents search for is some form of personal validation besides their parents and immediate family. It is probably close enough to true that we are biologically driven to look for this outside acceptance.
Unfortunately our society favors heavily segregating children based on age. That results in confused & clueless teens begging for acceptance from equally clueless people from the same wing of the same asylum.
Once in the real world a functional adult who can hold down a job finds there are a million ways to find personal validation. Teens do not have that opportunity; they (often) imagine that the opinion of other teenagers is the only path to validation.
Young people (13-21 year olds) should be seen as adults in training.
Instead they are given the role of adolescents, a role that they gladly take on. When you call someone an adolescent you set a very, very low bar. An adolescent doesn't want to grow, its pleasures are vain, its world secluded. The adolescent doesn't become an adult, since it is already "there" (the place that pop-culture glamorizes). Adolescence is thus seem as an end in itself.
Now if we lived in world where people didn't get old, and bills didn't need to be paid, we could all be adolescents forever and maybe there would not be any problem (though I would object on aesthetic grounds).
But the world being what it is, letting a young person live its youth as an "adolescent" and then forcing it to become an adult is a cruel thing. (And lets not forget all the kids for whom "adolescence" is far from pleasurable.)
In the past, adolescence was the onset of adulthood, period. In many parts of the world that's probably still true. It's our modern society that keeps young adults trapped in childhood until they're 18-21+.
That aside, I think it's the parent's responsibility to make sure their kids develop the capacity to function as adults by the time they have to start dealing with this stuff. Unfortunately that often doesn't happen, which leads to the problems you describe.
Maybe what we need to be doing is teaching the parents how to teach their children to be adults, through a medium that reaches both the parents and the children. We need "How to be an Adult" video games on mobile phones, perhaps.
http://www.amazon.com/How-Be-Man-John-Birmingham/dp/18759892...
It's written tongue in cheek but beneath the humor lies some great messages : you're all grown up now, start looking after things.
I can't remember if the author states any scholarly work to support the idea, but she talks about it at length. One thing that I think is well established is that kids mostly being around other kids all day is a relatively modern phenomenon. It's a long piece, but it resonated with me.
http://www.paulgraham.com/nerds.html
This is an incredibly insightful piece, one of the best. It talks about how, as a society, we shunt kids into a lord of the flies situation, and we force them to build skills that have little use outside the schoolyard. The problem is a lack of mentoring and not treating adolescents as people entering adulthood, but rather as a problem to be managed.
Lots of cultures have initiations and rites of passage, and into this modern void hazing, bullying and downright weird stuff has popped up amongst peers rather than elders.
I don't have the answer but it does cause a lot of problems.
I hadn't considered that specific viewpoint, yet it makes so much sense.
Furthermore, you won't be offended when others judge, reject, or humiliate you. Instead you will feel a sorrow for those who live in such a way, a sorrow that can hopefully be nurtured into compassion. If this sorrow turns into a holier-than-thou attitude, though, then we have a problem. :) The way to avoid this is through honest recognition of one's own weaknesses; once again, humility.
Emotions and opinions are fickle; the way people treat others reflects as much about the struggles and burdens they bear as they do about how they might "really" feel about something. To make ourselves beholden to other people's opinions and judgments is to necessarily strap ourselves to a roller coaster.
As someone who used to struggle with this a lot -- albeit unconsciously, because I was the one who was harsh towards others -- this is my experience.