Mitch O'Connell says:

First I tear the lid off the secret REAL origin of Scooby Doo – and now it looks like I'm about to get real again!

Almost 40 years before "M" came out with his film The Village about a hidden town of present day Amish-like occupants of a small Pennsylvania village who are made to think it's really 1897, and kept secluded by the woods from venturing into the modern (evil) world, it seems Action Comics #324 had the same plot.