It is true that in the long run, probably by the time everyone hits their early 20s, things even out. Talent has either presented itself or not and a year or so here or there doesn't really make a difference. However, along the way there are certain times that are more critical to "career path" than others.
Freshman year of HS is one of those times...it is where a player starts to develop his reputation. If a kid who re-classes is more likely to separate himself as a freshman he has given himself a leg up that he can leverage going forward. He still needs talent, and still needs to work. And there will be late bloomers...reclassing doesn't provide any guarantees...simply an important leg up at an important time.