Technology

Usability.

Windows and Mac are both easier to use for the standard user.

Not at all true anymore for Windoze. Windows 7 was the last installment where that was true. Linux distributions are consistent. Once shown how the basics works, e.g., apt install or pacman -S and the general whereabouts of settings or software, it's super easy to get them going, indefinitely. Even troubleshooting is within reach because searching the settings isn't a maze within a maze (except for Gnome sometimes). Windoze keeps changing shit constantly, reinstalls uninstalled software, search algorithm is horrible and has Bing search results within the menu enabled by default [the fuck?], updates don't indicate how long they'll last, setting a default program often requires configuring it manually for every file extension, oh goddamn fuckers I have to stop typing because Microsoft pisses me off so bad.
Tabula rasa, if I had to teach a 70-year-old who's never touched a computer before, to do so, I'd pick Linux every time. Consistency and customization is key. Microsoft makes their users dumb by an illusion of convenience which shatters the instant something goes wrong, like riding a bike with helper wheels that constantly fail. Linux does none of that. It empowers users quite quickly by simply learning how to ride a bike properly. Sure, you fall every so often at the start, but that made mastery that much more satisfying.