"Fairy Tales don't teach children that Dragons exist..."

I've become aware that I'm not the only one who was rather drawn to the quote at the end of the Criminal Minds episode "Seven Seconds". "Fairy tales don't teach children that dragons exist. They already know that. Fairy tales teach children that dragons can be slayed." Now perhaps I'm just different, but where other people consider the dragon(s) from the quote to be a metaphor for the "bad guys" in real life. However, when I heard the quote I took it to mean that the things we look at to be fun and/or important, can actually be very harmful, i.e. Fairy Tales.
Children have something that no one else in the world has, and that's innocence. As children we don't truly understand that people hurt people and things on purpose, but as we grow and experience things such as fairy tales that innocence slowly leaves us. So the quote, to me, means that as children we understand that good exists in everyone but the world teaches us that sometimes the good doesn't last in everyone.
To me the dragon is good even though some take it for something that should be slain. Children understand to give people a chance before they judge, but the world teaches them to judge before they have a chance to get to know it.