Isn't JavaScript turned on by default in most webbrowsers, at least the ones that a non-techie is likely to use? In that case, it's either already activated or if it's not the user must have turned it off herself - but in that case she should know how she did that and how to undo it, right?
Oh, well, perhaps one could say that at least this is a nice little reminder for those who have never used a menu or a preference window. ;-)
But wait, how would I even find this site when I need it? Should I bookmark it, just in case I ever turn off JavaScript and then forget how to turn it back on again? Because otherwise I'm sure googling "turn on javascript <mybrowser>" would have gotten me the right answer quickly even without this page.