Poor analogy Bob. Racing a real car is dangerous, expensive and against the law in public. Playing a real guitar is none of those things.
I think Uncle Bob's analogy works.
Hey, Instead of racing Karts why don't you race Go-Karts for real.
Instead of playing any Sports game play the game for real.
Instead of playing a First Person Shooter, play paint ball for real.
Guitar Hero isn't about learning to play Guitar it is a really fun rhythm and reflex game.