Pondered it a little, and i think you might be misreading some people unintentionally. Maybe you mentally match FGM to mutilation as a whole, which most people don't, and react to them as if they did? Note how something can be in the same class as something else, but have a much lower degree of impact. When someone says mutilated they may not necessarily be thinking "horrifically" or "barely functional". Heck, many people consider ear rings or tattoos mutilation.