I think you read the word "contrived" into a place where it was not. I think it's more like, "the characters heard legend that A could happen, but despite this

I think you read the word "contrived" into a place where it was not. I think it's more like, "the characters heard legend that A could happen, but despite this they need to accomplish B. And of course, at the worst possible moment A happens and now they have to overcome it." It's like nature's chekhov's gun.