Actually, they do.
Ideas propagate because people read about them and decide that other people like them believe them. The whole point about Facebook is that it is an echo chamber, not a free market in ideas, and it shows its readers what they want to be shown. No critical thinking involved. It hypes people up because the more extreme stuff they look at, the more extreme stuff they get shown.
And don’t talk to Germans about learning from history. They have done so rather more successfully than the US, and as a result have a more cohesive and equal society. Germany has gone from the scourge of Europe to being the country that does the most to unite Europe. The US, meanwhile, is by far the biggest destabilising influence in the world with its constant wars in the Middle East, and is still unable to come to terms with its past of slavery. I’m not German, but I admire what they have achieved.