Early Crusades beg to differ. Everyone would hear a really distorted version of this "persecution" and then go on a huge march and kill some unrelated people about 5 years later.

Local anger? What a weird way of saying public lynching

Because there was no social media at the time though it would certainly spread slower. And I doubt it would be forgotten given how long the “blood libel” conspiracy has been kicking around and causing massacres throughout history.

Technologically yes.

Many people still base their morality on mythology from the Iron Age. Blood libel conspiracies still exist.

We didn’t evolve into a better human when we ended the medieval period. We’re still the same apes prone to the same fallacies and environmental pressures.

You just want to feel like you’re intrinsically above this behavior, which is a naive way to view human thought and morality. Given the right circumstances you could easily turn out just like them.