It has more to do with the idea that authorities will decide what they want to do then recruit words from anywhere they can find to justify it, than it has to do with what those words say. (See also: Crusaders using Jesus as a rallying symbol for mass killings of civilians, 1920s American eugenicists using the science of heredity to justify racism followed by 1930s Nazis who developed on the theme, 1980s Regan administration selectively using basic economic ideas to dismantle public welfare, while staying silent about corporate welfare.)
It is limited to authorities in the history books because by definition when non-authorities do it, it doesn't go very far. :-) No matter how much a medieval peasant hates the Franks, nobody will ever know.
