They never managed to get it working for their liking, it wasn't able to run the stuff their friends used to talk about or share via CD/DVD/USB sticks, and they did not wanted to bother me with "dumb" questions.
So I rather that they have Windows, go down to the local PC store when something isn't working as it should.
It's been a while since I experienced people sharing software one discs by the way, it's been a while since I saw discs at all ;)
Only if the device is truly 'forgotten'. As in, it is an appliance that's going to do that task forever and ever. Be it web browsing or what have you.
If requirements change, it becomes a problem. If they have to do work on them and interact with companies, you may need either Windows or Linux. Thankfully online Office365 removed a big use-case. But there are others. It is very likely that whatever package you need will be available on Windows or OSX.
macOS also has (well, had) extreme UI stability. You could transport someone from 2003 used to Mac OS X 10.0 two decades into the future and they would be able to use macOS Ventura (and all previous versions) purely by muscle memory. Good luck doing that with Windows and Linux with their constant UI churn.
Interestingly enough, by iOS-ifying macOS, they've made it much easier to shift someone using an iPhone from Windows to macOS, because they already recognize many of the UI and UX paradigms.
When I say it's been fire-and-forget, I mean that for at least two decades.
If papercuts turn up, you are running the wrong distro or secretly a power user that naturally causes problems for themselves every now and then. This won't happen with normal users on a long term stable distro.
Once it's configured for these kind of people, it's really fire and forget, and it was already that in 2016.
She did go back to fix things because the grandma managed to delete the printer, and she said that the downloads folder was full of exe files with sketchy names.
I'm with you on the macOS stability in the past. The thing that gets me is that Windows somehow gets a pass in this regard, but there have been some pretty big changes over the years.