I thought this was an interesting hypothesis, that the inability of coporations to use aptitude tests on potential hires (something that has been effectively killed by civil rights suits) has led to the increased reliance on college credentials as a screening mechanism.
I think there is an element of truth to this, but I suspect this would have happened anyway as the presure to cut costs caused companies to push their candidate evaluation and screening onto other institutions. As I wrote a while back
There is some rationality in this approach [to hiring mainly from the Ivies] – it is not all mindless snobbism. Take Princeton. It screens something like 25,000 already exceptional applicants down to just 1500, and then further carefully monitors their performance through intensive contact over a four year period. This is WAY more work and resources than a private firm could ever apply to the hiring process. In effect, by limiting their hiring to just a few top schools, they are outsourcing a lot of their performance evaluation work to those schools.
I don't know if these percentages are entirely correct - I would argue the education / skills component of my mechanical engineering degree was higher than 10%, but that may be just my personal bias - but the basic approach seems sound
Peter Thiel describes higher education as a "giant selection mechanism" and estimates that only 10% of the value of a college degree comes from actual learning, and 50% of the value comes from selection (getting into a selective university) and 40% comes from signalling (graduating from a selective college becomes known to employers). If employers could use intelligence tests instead of college degrees as measures of aptitude, it might be a lot more efficient and more cost-effective than the current practice of using very expensive four-year college degrees that add very little in terms of educational value (at least according to Thiel).