If I can disagree a bit with the image at left, increasingly, we don't learn early on how to deal with rejection. It seems the self-esteem factories of childhood are dead set against letting young people experience anything that could be seen as rejection or a repudiation of their innate wonderfulness.
I am writing this from the very un-objective point of view of someone who just got a rejection letter for a short story he thought was pretty good. But despite my anger (and there's no other word for it) that some hack assistant editor decided my story wasn't worth the time of day, rejection is clarifying. And I don't think we have enough of it in our modern world, especially for young people.
In the worlds of academia and youth activities, we have worked hard to ensure that relatively few people are told their work is inadequate. There's a paint-by-numbers way to get at least decent grades, and there's always an activity willing to celebrate your effort. (Sports remain something of an exception, but only because putting lousy players on the team only delays rejection until the actual game, when you get the ultimate rejection of losing.)
Grade inflation is perhaps one of the more insidious ways that a culture of non-rejection ruins people. A smart student that gets B's and C's because their work isn't quite up to the level of top achievers might be motivated. But when everyone who is adequate gets an "A", the underachiever has no motivation to improve and the overachiever feels cheated and stops working as hard.
Even in dating, perhaps the area most likely to create rejection, the challenges have been lessened. When most people dated with some degree of commitment, the decision to be with a person or not was serious, and a lot of feelings got hurt. Now, young people increasingly have to live with a hook-up culture that discourages serious commitment, but opens the door to casual flings where no one's feelings are hurt, but no one leaves quite satisfied, either.
In adulthood, this translates into no one being willing to tell you that you could be better. I had a long conversation recently with some managers at my company, who said that they were trained to treat anyone under 30 with kid gloves and to overwhelm them with positive reinforcement, lest they become discouraged and quit. Unsurprisingly, those 20-somethings don't seem to be learning how to get better.
That's the value of rejection: it either clarifies your failings or makes you that much more determined to prove the rejector wrong. If we are losing our ability as a society to reject that which we feel is inadequate, we will end up with steadily less excellence, as too many talented people will feel their first, mediocre efforts in their chosen field are good enough. Far better to maintain a culture of high standards, where a little rejection goes a long way to motivating people.