Shit's better now. That's not to say that your average person could handle everything.

If I have a normal person linux on a usb on a computer set to boot from usb, they could totally install it.

If an update fucks over a driver or a package, they're completely fucked.

If they need to make their own boot usb, they're completely fucked.

If they need to configure their computer to boot from the usb if it's not setup that way ... completely fucked.

If they're good with generic drivers, generic browsers and probably steam, they'll be fine.

Grandma is probably fine with Linux now.

Of course, a decent number of gen-x grandmas might have actually fucked around with linux years ago :)