That's an easy one. Millenials like it because they are completely ignorant about history.
An old friend of mine once described the shock he felt when he enrolled in a top (expensive) college and learned how utterly ignorant his classmates were about history. To his average classmate, history was (in his exact words) "a jumbled mass of cavemen and people riding in covered wagons -- and not a single clue about the general times in history when things happened relative to each other."
Forget about Millenials. This all happened DECADES ago.