Some people are out on the blues to challenge themselves and/or see what they are missing. Some are following their friends who have overestimated their ability. Some might have been confused a junction and gone down the wrong trail by mistake. If we banish everyone to the greens until they are 'good enough' (according to whom, by the way) we won't have any new skiers because they will be bored and lack incentive to improve. We sorely need more skiers to maintain the sport we love.
I don't suggest banishment to an 'i cant spel or typ four the life of me' site for poor grammar, spelling and punctuation on this site. Rather, I'd encourage the use of the spell checker, utilizing adequate punctuation and fixing my shift key. The same goes for skiing. If you can't ski to the level that you need to on a run, that's ok. You are on the hill to have fun and enjoy yourself. That isn't to say that you should be a reckless idiot, either. As a professional, in uniform, I'll offer help to someone that is clearly distraught and at high risk of injury. I often will do that out of uniform, as well. It is akin to asking someone if they are ok if they just wrecked and might look a little bleary eyed.
Empathy can go a long way towards reducing your frustration with others apparent lack of consideration. I was a beginner at a number of activities throughout my life. How about you? Think about how it felt and then imagine how the the other guy might be feeling.
Edit: FWIW I found 4 spelling errors in my original post with spell check. Edited by MastersRacer - 3/14/10 at 5:43pm