If Fable (Mythos) were generally available without guardrails, it would cause enormous damage. Nobody said it would be a world ending event.
You can’t say something is world ending without it actually ending the world otherwise you’re a liar - a bit of a catch 22 there.
By that logic the model that ends the world won’t be called world ending at first. Is that a game you want to play?
What about Mythos 3. Are you willing to make that bet?