...that's not all that's going on here.

The cross-tab on age here is telling in that younger folks (who are more apt to be Dems) are more apt to agree with the statement than older folks, but that can be explained at least partially by education and proximity to the event. A 25-year-old today was in high school in 2015, which is 70 years removed from the Holocaust. That's comparable to a high school student in 1980 being knowledgeable about an event that occurred in 1910, and I bet a lot of 25 year-olds in 1985 were a little fuzzy on world events in 1910. Further, due to wokeness, history is taught differently today than it was in years past.

Sidebar: A fascinating poll question would be to have randos rank the following world events in terms of "deadliness": A) The Holocaust, B) Russian communist revolution, 3) China's Cultural Revolution/Great Leap Forward, D) Rwandan genocide and E) Cambodian communist revolution. I bet you'd get some interesting responses to that.