People say:Why didn’t Pope Pius excommunicated Hitler who, after all. had not attended mass since he was 17; who in fact, made little secret of his contempt for the effete religion of Christianity. Because he knew that faithful Christians in Germany were in the minority, and that to denounce Hitler would only strengthen Hitler’s hand.
It would have been been superfluous. Hitler, by his own actions, had clearly excommunicated himself, latae sententiae.
What most do not understand is that excommunication is not intended to be punitive. Its purpose is medicinal. It is meant to guide the recipient towards reconciliation and a return to communion with the Church.
Peace be with you
Probably because they never learned that the Nazis were excommunicated en masse by the German Bishops in February 1931.