Before 1960 or so only about 10% of all 18 year olds went on to college. It was just assumed, and I believe subsequent experience has amply prooved, that only this small fraction of young people could be called “college material.”
Not only that, college was tough. Even in the mid-'60s, unless you could take a full course load and pass, you didn't get to stay. It was pretty much a full-time job to do well.
The question that has no answer is why poorly qualified students would get into college, be offered loans, and accept them. Students should be accountable for what they do or don't do in HS. Until that happens, achievement isn't going to happen.
FWIW, the top 5% or so is more qualified than ever. The intelligent, motivated students understand that they have to be incredibly well qualified to get into colleges and courses that aren't a waste of time.