What a lot of people who say things like that though is that witch hysteria was often a girl-on-girl crime, and not just women who were pressured by men accused other women of being witches, unfortunately.

I have two possible reasons for that. 1 is that then she may have to come up with a magic system for her series, instead of what she has now. But that doesn't really make sense because she already gives her Sue and her Nakama elemental powers, but maybe giving all the witches magic powers would lessen their speshulness. Reason number 2 would be that she's mooching off of Twilight.