Then perhaps we should make "percentage of graduates who are able to make a living in their degree major" a metric used in accreditation. Or at least have the government PUBLISH, broken down by college and major, the percentage of graduates who are behind on making their student loan payments. Then pull accreditation of any college program which has defaults rise above a given threshold.
The big problem is that colleges are admitting people who are not qualified for college, and letting them graduate from programs that do not demand rigor (and thus are easy to graduate from), rather than either not admitting them in the first place, or flunking them out in freshman year (before they've invested excess time and money in something that won't work out).
No one is demanding that these students go to college; no one is forcing them to select their fields of study, or finance their education via means of student loans. There are simply too many variables of which the college or university has no control over; e.g, the number of times a student changes degree programs, the amount of "waste" in how a borrower may use their student loans, the student's willingness or ability to enroll in a degree program with a better employment outlook, etc. It might even come down to something like "relocatability" -- is the student willing to relocate to a different geographic area upon graduation, if it meant better job opportunities?
You threaten to employ a pretty heavy hand for a situation that could work itself out in a more private, free-market solution. Accreditation is suppose to speak to academic standards set by a university, not the financial aptitude of its students.