From Phi Beta Cons:
If you go back more than 40 years, you find that few occupations were closed to people who did not have college degrees to their names. What changed? In short, I think it was a combination of these factors: the erosion of high-school standards (which used to bring about at least respectable basic competence in young people but began to slide in the ’70s), the subsidization of college, which led to more and more people earning degrees and thus casting doubt on the capabilities of those who did not, and the Supreme Court’s decision in Griggs v. Duke Power (1971), which turned testing of job applicants into a legal hazard for employers and thus encouraging them to look at a safe alternative means of identifying individuals who might have the right characteristics.
As an employer, I have to agree with all of the above.