The problem isn’t that it’s possible in some distros with some tinkering, albeit that warning would scare the shit of someone that is used to computers, but not a Linux expert yet (ex : me), let alone your average normie user that can’t do anything more complex than change their wallpaper. The problem lies in the existence of such a system in itself in the modern day single-user centred computing. I simply can’t fathom a reason for it to be this way other than a holdover from the past, back when Linux was only for companies and servers.