The devaluation comes from the glut of supply.
In Canada I watched as credential creep happened to the point that you needed a minimum of what Americans would call an "associates degree" (or some such thing—the three-year thing you mentioned) **TO ANSWER TELEPHONES**. All the people going out and getting degrees didn't get jobs related to their degree (because there's a finite number of these, typically). Degrees just became Yet Another Hurdle To Jump to get employed at all.
