It was brutal, but one of the most educational classes I've ever taken - and obviously not just …

Part of the issue is with the purpose as you describe it. Sure, at top 10 schools, a trial by fire would result in much needed “growing up” as the gifted but undisciplined (speaking for myself and many users of this site) students find their way to more durable motivations. But at the vast majority of schools, a trial by fire would end with a lot of students burned. Perhaps that begs the question, if those kids can’t handle self-directed education, why are we putting them there in the first place, but that’s definitely a grey area, and there are hundreds of thousands of students who are smart enough to do well in higher education and skilled work, but weren’t disciplined enough to handle what you’re describing as freshmen.

The idea of "weeding out" students implies that many students are "weeds" who need to be uprooted and thrown away rather than grown. A teacher who thinks this way is probably in the wrong profession. A university that operates this way is failing to educate the students it admitted.