Let me explain a line of reasoning that would refute the explanation you provide for the ballooning debt. Universities have not generally changed the way they do things, universities have always been the four things OP listed since forever, even when you likely got your degree (assuming you did, or at the very least most of hacker news did), they were those four things too! Therefore, there is no inherent thing to universities that explains the ballooning debt. Instead, something must have happened between the 90s and now that correlates with the rise of debt. Thus, look for an explanation by looking at the history of policy rather than relying on rationalizations.

To that end, a quick google search yields an article that gives a good set of reasons a think-tank that studied the problem found as a set of causes. This is the first result of googling "what caused the student debt crisis":

https://www.businessinsider.com/why-is-the-student-debt-cris...

Now those four items ARE things that have changed between now and then. Generally, the decline state funding of schools means unis now fund themselves by relying on tuition that students do not feel as a cost (at least immediately) because the federal government can give out loans like candy.

Again people, please please please don't just conjure up ideas in your head and think you understand the causes in the world that explain how everything works. You would not apply this line of thinking to your own job you are paid for, people have studied these things and generally it is understood why the debt crisis exists, it isn't a mystery!