Totally get it, however, we're talking about Windows 7 + LibreOffice users here. Twenty years ago, installing GNU/Linux on someone's computer meant replacing the supported OS that everyone got with an unsupported one, and everyone got it, even people whose first experience with a mouse was to hold it in the air and point at the screen with it.
Things have... changed in the last 18 years. Computers have gone to crap. Normal users no longer know what a file is. Microsoft Office has changed its UI so learning it literally means you've only learned how to use Microsoft Office and not word processors in general.
But... the people under discussion, the people running LibreOffice - which is a CUA application with drop down menus and consistency throughout - and Windows 7 - which doesn't hide the file system from you under a mountain of OneDrives and other shit - have had time to learn how to use a computer.
Their support load is going to actually be minor compared to the boomers you were supporting 15 years ago. They already know how to use a computer. Give them a MATE UI and OOo or LO, and they'll be happy. They'll probably even customize their own desktops, and appreciate the fact they can.
And if, for some reason, they don't fit into that category, their needs are going to be so inconsequential you're only going to get a call once in a blue moon about whether they should accept the offer to install updates or something similar. They'll not be plugging in new hardware outside of replacing their keyboard, mouse or, at worst, their printer. The support for that should be pretty minor too if you encourage them to make their next printer a Brother laser.
The world has changed. Mostly for the worse. People are getting dumber. But, ironically, people who stuck with the same technology since the late 2000s probably know quite a bit more about how computers work than those being intentionally confused by UX anti-patterns, "algorithms", cloud shit, and so on.