Every culture has some fear of "typical" men flowing in its undercurrents. But only in the USA, AFAIK, this fear has been able to mobilize so successfully such central institutions as the government/president, military, and universities, perhaps also the law enforcement and justice system. Nowhere else have I seen the idea of "typical men as rapists" become a part of the popular discourse (=allowed to be expressed freely) the same way as in the USA.

Am I mistaken? Where do you think this peculiar and very harmful idea came from?

("Rape culture" is often used as if it described the reality itself. As I see it, it's clearly a representation that's mostly backed up by ideology, false statistics, media hysteria, and moral panic. Every reasonable person should be interested in fighting rape culture in this latter meaning because it harms everybody and young men and women in particular.)