I've been using Debian GNU/Linux with KDE as my main Desktop from 1999 (21 years now): in home and work. As a "family administrator" my father use Linux in the Desktop too from about the same time. My 2 sisters and my brother also use it all the time. If they have any problems, they call me and I'll take care of it. I got married in 2004, and since then my wife and in-laws have also used Linux on the desktop as their only operating system.

My oldest daughter is 16 years old and has always used Linux at home, and she had no problem when Windows was found in some classes in the High School. I think it is possible, as long as you have someone to turn to if there are problems (I am that someone in my family).