Universities always have been a system for selecting people who can keep it running in the future. So the first day as a freshman kicks off a test of serveral years if you're a fit. That's why we have different levels of degrees. People can drop out without much sunk costs. Otherwise only very few would try this journey and then the base for selecting good people would be low.
What I mean with good people who keep it running has changed a lot. Historically, universities didn't have to justify themselves much. For governments, it was obvious because they provided knowledge gain, and, primarily, they provided well-educated people to work for the government. So universities selected the best people because they would become the next generation of teachers or drop out as educated governmental workers.
Nowadays, the government and the public want to see research results (for funding) because this is supposed to be the purpose of universities. I think this is a misunderstanding and universities took part in creating it. So the people universities select for now are still good students but also ones that play by the new rules and crank out as many papers as possible.
My main obstacle during the PhD was to adapt to a research style of looking up fashionable topics in the research community, writing an incremental paper und publishing it. My advisor even objected against some ideas because they're too risky.