Public schools have indoctrinated us to where we diminish it, and therein lies the problem.

You're comparing two different things. 8th grade "graduation" is not about necessarily acknowledging the accomplishment, rather it's about acknowledging the actual progression from 8th grade to 9th grade, which in many ways is a MUCH bigger progression than from 12th grade to college. But public schools see it merely as the second year of junior high, even going so far as to sometimes have Grades 7-9 junior highs.