Bob the Postman. Thank you. I've tried and tried to do that.

Hello Rus. I don't believe the simplified answer works. You're quite right that it's a common answer to this question.

I'm with Brian about people not having to believe in the supernatural to use it and enjoy it. Much of the drama in songs, plays, literature, poems, depends on taking people beyond the every day world.
I'd begin to answer your question by saying tentatively that a high point might have been during the 17th and early 18th century.
I'm not a folklorist, though. Just an interested observer since I was a kid.
Cheers, Joy