They're only cheating themselves in a world that increasingly cares about knowledge (market trend of seniors being preferable hires to fresh out of school juniors) and not the piece of paper that "proved" you had such knowledge.

I agree with you that they are cheating themselves. Unfortunately, a bunch of 18-22 year olds also don't tend to have the maturity to realize that fact. I imagine that the university is trying to nudge them to do the courses in a way that helps themselves because they know otherwise the students won't be wise enough to do that.

These students are making a tradeoff between an abstract notion of "cheating themselves" and a very concrete notion of "having a worse GPA". The second one translates obviously and directly to job prospects.

they should learn as much as they can + cheat for optimal results

Not really. If they got admitted to Stanford to begin with, they are smart enough to succeed if they put in the work. So what they are actually trading off against is "I don't want to do the work", which is far less defensible than your reading of the situation.