To paraphrase Aristotle, audiences find it easier to believe an impossibility than an improbability.
So Superman being able to fly and shoot lasers out of his eyes isn’t as world-breaking as if he found the guy he was looking for bc he happened to get in the right Subway car
How it feels to not believe "Gaster created Deltarune's world ex nihilo" OR "Gaster hijacked and changed an already existing world" but a secret third option