The context under which certain practices became entrenched, while interesting, is irrelevant.
If it's mostly Muslims practicing FGM today, who started it centuries ago doesn't matter. Centuries ago, all humans lacked medical knowledge, they lacked human rights awareness. This is not the case TODAY.
"Christians used to do it centuries ago" may seem like a great excuse and discussion ender to you, but it's not for me. The world has moved on. Islam has not.