Actually, there's often not an issue when you criticise how a properly defined and specific cultural system might harm people (eg evangelical home-schooling, FGM). The problem is when you think "culture" means "millions of people grouped under the same label are homogenous and can be ranked somehow"

(not that there aren't absolutely racist ways of framing and discussing FGM, but the prevailing opinion has never been "you can't criticise something like that at all"!)