Perhaps the point was never to educate, but to differentiate. Peeling off the top 10% has it's own value.
"Caplan argues that the primary function of education is not to enhance students' skills but to certify their intelligence, conscientiousness, and conformity—attributes that are valued by employers. He ultimately estimates that approximately 80% of individuals' return to education is the result of signaling, with the remainder due to human capital accumulation."