Counter-counter nit pick: it's still not accurate because a piece that stays in C Major all the way through can still use notes outside of the C Major scale (eg

Counter-counter nit pick: it's still not accurate because a piece that stays in C Major all the way through can still use notes outside of the C Major scale (eg passing notes) Also I would say "X is simply Y" means "all X does is Y", but I guess this isn't universal