What is the probability that a person without a diploma can read? You see, its a credential that means something to people who do not know the person. Even if the difference between the probability a person can read given a diploma and one without is shrinking, it still has value. Furthermore, I remember a lot of what I learned in college. What I dont fully remember, I still remember the basic concept. This aids me in a general understanding of what is possible, knowledge of possible solutions, and furthermore, if I actually need to know more detail about it it would be very fast to learn what I had forgotten (like a cache miss).