I think these days it’s a bit different in that many schools allow high schoolers to apply directly to the CS department? But then it would be a matter of scale I guess, they usually have clinical professors run these classes because they demand full time attention.
I don't think it's completely wrong. Failing a student after he or she sunk a ton of money into it is really not ideal. IMO it seems really easy to pass prospective students the first few chapters of your CS textbook/lectures then test them as a prerequisite for enrollment, before they enrol. This would be close to free, filter out a lot of would be dropouts and just save money and effort all around.
1. Back when I was in CS, the department was much smaller than it was today. This was after the 80s programmer crash, and so they just didn't have enough professors or resources to teach as many students as were interested in being CS majors.
2. You are able to teach to a higher standard if you've filtered the students that enter your department. You can have one or two people fail OS rather than half the class. At some point, it is reasonable to see if the students are committed, and they get to prove themselves a couple of years after high schools, which worked better for people like me who weren't very accomplished until they get to college.
I sort of like the change to redeem yourself during the first two years of your university if you didn't have the ideal secondary school experience to get into a hot department of a hot university. CC can do that as well, I guess, but it is a much harder hill to climb.
At my university, after the usual calculus/diff eq/lin alg sequence everyone in STEM takes, we had “intro to advanced mathematics” that was proof based, taught in the spring, and a pre-req for everything higher level (abstract algebra, real analysis, etc). Most math programs have a similar “first proofs” class as their “weed out” class.
But intro STEM math is used as a weed out for other majors. You aren't going to get far in CS if you aren't able to ace your basic calculus classes.
