Linux would have to be extremely good for most people to take the effort to switch. Switching to Wikipedia doesn't require reformatting your hard drive and installing a new operating system—a completely foreign concept for 98% of the computer-using population.
Reformatting your hard drive and installing a new operating system is just the beginning of it.
Such a drastic change of OS basically disrupts your whole workflow while you get used to the new one. Everything from where to find things to keyboard shortcuts to UX paradigms.
