I remember when I was 10 or 12 or so hacking with my IBM 8086 and using basic, I accidentally "invented" the bubble sort. In fact, mine was extra slow and inefficient because both my outer and my inner loop went from 1 to N and there was no early exit if no swaps were made. A true O(N^2) algorithm. I didn't now what O(N^2) meant, but I had some understanding the things quickly got slower.
Then later in CS101 I learned about big-O and all the theories around sorting and it immediately clicked because I had a deep understanding of something that I experienced and then could tie it to real theory. The other way around - learning the theory before the experience - wouldn't have worked as well.
To tie it to your comment, you should have a deep experience with your OS of choice and then when you go to school, you learn why things are the way they were.
When I say this I often get accused of gate keeping, but I don't view it that way. I look at it as other types of majors that have existed longer than CS. I often make an analogy to music majors. I can't enroll as a freshman and say I'm going to be a music major without ever having played an instrument. People get accepted to a music department after they demonstrate the ability (usually though the equivalent of hacking while they were kids), and in their music classes they learn theory and how to play different instruments (just like learning different OSes or languages).
I kind of feel that CS should be the same way, you should show up to CS101 knowing how to do things from deep experience. You may not know any of the whys or theory, that's fine, but you should have experience in doing.
To tie it back to the parent: you should come to CS knowing how to run Linux, maybe because you copied configurations or scripts from the dark corners of the internet. And then the CS classes should be around why it's all that way. E.g., you know that to schedule something you use cron; and CS would be a discussion around how generic OSes need a way to schedule tasks.
Anyway, when I made the comment, I was thinking it should be an elective and intended for people who either aren’t that familiar with Linux or want to become even more comfortable with it. There are certainly plenty of such students in my experience, myself included when I was in college.
Also just to be clear, this shouldn’t be just about “being able to run Linux at home” level of material, but things like writing non trivial applications using Linux subsystems and being able to troubleshoot them.