But even students treat it as such. Many of the people I know went to get a degree because they believed "they had to", not because of an intrinsic desire to learn. And if all involved believe that it is about getting a qualification for some career, then that is what it will become.
>when higher education in the UK was fully-funded by the state the resulting degrees, regardless of the subject(s) studied, were far more valuable in the job market
Rarity is the actual important thing here. If a significant portion of students have some degree it will be inherently irrelevant. Education has been continually broadened, making it more and more irrelevant. In the past a university degree was an enormous signifier, now it is "expected" in the job market, even if irrelevant.