And I definitely think you're off base about mobile devices being popular because they're mobile. People will sit at home and use a phone that is an incredibly worse experience than using an actual computer, and think it's an adequate substitute. They don't need the mobility in that situation, but they really think there's nothing wrong with the user experience.
I’m not exactly the demographic of “only uses mobile” - I am very much a “pre-mobile internet user” (coding, games, music all required me to pick up some desktop skills) but can attest to the fact that I don’t hate the experience in a way that’s commensurate with how much I’d hate having a hot laptop on my stomach or sitting in some other room typing this out.
At what age does someone need root access to become interested in a career in CS/IT/web dev/whatever?
Or, if not root access, like what kind of "desktop level capabilities" should I have had that I did not have, given that I did not have a desktop as a teenager or younger?
I am Gen X. I can think of exactly 0 friends who had their own desktops as teenagers. (Their own, as in were not really their parents' work computer, did not have to share with the family, could do whatever they wanted with, etc.)
https://www.theverge.com/22684730/students-file-folder-direc...
You do not need root access necessarily, but you do need to get familiarity with the platforms you will actually be using when working, ie. Windows and maybe macOS.
For Gen X and most of millennials, that platform was the only platform that existed. Using computers necessitated becoming familiar with "real" computers. That is no longer the case which is why gen Z are digital natives that have the digital literacy on a similar level to baby boomers.