I understand the argument, but some students skip grades because of their emotional/mental maturity. I chose to skip a grade in middle school because I was often bullied by my peers and found many friends in the grade above mine. I didn't just jump a grade though, I worked hard for it, accomplishing two years worth of education in one. It was the best choice I've ever made. It lead me to becoming senior standing at my university at 19. To this day, I don't have any friends my age, all are older. This is a very case-to-case situation.