[flo123456]

Whichever for me was in 2010 when I set up Ubuntu for my grandma and put a Firefox shortcut on her desktop and she never had any issues with her computer again. Very simple use-case but it was a lot better served than by Windows Vista at the time. These days it’s even better served by an iPad though.

[fluoridation]

IME, that works as long as the user does nothing but browse the web and nothing in the environment or the computer changes. Things get tricky the moment any of those assumptions are invalidated. And that's because the user is not really operating the computer, but just using it to access the web. That it's a "desktop" is only an implementation detail.

[segasaturn]

By that metric the Year of the Linux Desktop was in 2012 with the introduction of Chromebooks.