Probably very useful for setting levels in lessons -- if you're above 6 you probably aren't a potential customer anyway. But I find it funny that I'm a 5/6 on that scale, and I've got so far to go before I could keep up with a lot of the people on this forum.
I told my kids, "Someday, you'll have kids of your own." One of them said, "So will you."
-- Rodney Dangerfield.