Of course they are a proxy, but they are much better and cheaper proxies. I was assuming that credentialism would remain - examination-based degrees make credentialism much less costly.
I don't see any compelling reason for thinking that the degree of knowledge that can be measured on a one hour (or even a five hour) exam is comparable to the degree of knowledge that can be measured from a larger body of work (whether that work represents continuing interaction between an instructor and student over the course of a semester, or a self-directed large-scale portfolio project).
I'm probably showing my age here, but in the heyday of Novell there was a phenomenon called the "paper CNE". The military has long referred to those who've gone through an abbreviated officer training process as "ninety day wonders" (not a compliment). Other examples abound.
