Many for-profit degrees are not very worthwhile. There are surely some exceptions and I think healthcare professions type jobs might be those; although they likely don’t pay much (if at all) more than the librarian job in the OP they also cost much less than a BS plus an MS from a university.
I agree with your point that many majors in nonprofit universities are also not especially useful in getting a job. That is not universally true either, however. Plenty of good jobs will consider people with degrees outside their field if they are smart and willing to learn.
We have a gal in our accounting department with a library science degree who is great, for example.
One problem we have is that because of the way funding is structured universities don’t charge more for degrees with better job prospects than they do for degrees with worse prospects and it is no harder to get a loan for an English major than it is to get one for a business major.
Further it is no harder to get a 200k loan to attend Thomas Cooley Law School than it is to get 200k to attend Harvard. We treat the two as fungible even though we all know they are not.