Don't underestimate the much-maligned high school diploma.
Sure, it doesn't take kids as far as it used to, but it's far from meaningless. Anyone who's sat through a graduation with sobbing mothers, camera-clutching fathers, stepparents, aunts, uncles, grandparents, godparents, friends and neighbors knows that floppy piece of paper carries a lot of weight.
If a diploma isn't important, why do graduations attract so many people?