If that was the real requirement companies are interested in then wouldn't someone working variable shift at a fast food restaurant proving that they can "adult" just fine? Those jobs have very real repercussions for not showing up even once unlike college.
At my Uni (my major, that is), there were exactly zero classes with compulsory attendance. What would happen was this: First 2-3 weeks were packed with students, then it would thin out, and two thirds into the semester you'd sometimes have only a dozen of students.
Come last lectures and class review, lectures would be packed.
That is even more relevant today, with video / streamed lectures.
With some notable exceptions the classroom experience was pretty poor and all of the information and resources were readily available on the internet. And if you're not the best autodidact there were plenty of study groups were students got together and figured things out just fine.
That said, I still think self-directing yourself through that kind of environment takes a lot of agency and skill, agency and skill that companies require for jobs where neither ageny or skill of that magnitude will be required.
Most jobs don't require time management skills beyond "be at this building for 9 hours a day".
Of course that's a very poor proxy (some people live at home while getting 4 year degrees, etc), and often times college becomes more about signaling you're part of a certain socioeconomic background (with all the subtle discrimination that entails).
Either way, even if the things you learned are entirely irrelevant to the actual job, a lot of employers look to it as a very rough signal for "had things together", and have a set of beliefs about people who have them.