My guess would be that it gives students the unfair advantage of more study time? Where I studied (Norway), university students would regularly fail on purpose

My guess would be that it gives students the unfair advantage of more study time? Where I studied (Norway), university students would regularly fail on purpose on the first exam, so that they could get two-ish months more time to read on the subject, as the re-take/postponed exam would be around August/September, or January/February - depending on semester. It was/is called "strategic re-take", and unsurprisingly, you'd always see a bunch or A grades on the re-take. Same thing happens in the high-school level. People that want to study wildly popular majors, like medicine, will spend YEARS re-taking HS classes/exams to polish their grades. Those studies are so competitive that you could get almost straight A's, but still not be good enough.