I didn't read the rest of the thread, but a major impetus for this particular part of federal loans is because students in the past - most notably our medical colleagues (thanks!) - would declare bankruptcy and have their debt discharged. For physicians in particular this wasn't much of a problem, especially those going into fields with many years of training. The scheme would essentially look something like this:
-graduate from medical school
-declare bankruptcy, get most/all education loans discharged
-complete residency; at this point, you likely aren't going to be buying a house, buying a fancy new car, etc. which would require a decent credit history. During this time, you're counting down the 7-year limit on having that bankruptcy on your credit report.
-depending on the field, you finish residency/fellowship and have either surpassed that 7-year limit or only have a couple of years left before that limit is met
-congratulations, you're now making an attending salary - in the "golden age" of medicine no less - with no education debt
We have our predecessors to thank largely for this provision.