Comment: I think "myth" is entirely appropriate here.

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In reply to comment: While a myth is often equated (see in situ)

I think "myth" is entirely appropriate here.

There is lore built up around the false story.

There is a moral, but it isn't based on any historical events.

So I guess you could say it is a "false mythology."

And hidden in that fact, is yet another moral - don't believe everything you read online.