Apart from the notion of a moral obligation that may now seem quaint and old-fashioned, you’re talking about their customers who are paying for an education. The responsibility rests partly on the school for solving these challenges. Declaring students “weeds” would tell you all you need to know about the place.
I'm sorry but this is straight up a non serious reply. If you want to be in STEM you need to pass calculus, then the specific majors have their own "weed out" courses which is good. There should be some base level of competence and if you can't pass, say, Abstract Algebra then you can't get a degree in mathematics.
There needs to be some sort of academic baseline for university otherwise what is the difference between a youtube playlist and a semester worth of credits?
If it's simply pay to win then the value of a degree from an institution falls to absolutely zero. If the product a student is buying is a credential that's supposed to say "I know and can do things, pay me money please" then in order for that credential to fulfill its objective then low performing and mediocre students ("weeds") need to be filtered out. Otherwise, employers and the wider world will quickly realize the credential is meaningless.
See the problem here?