Besides the brutality of it, it is a rather good tactic.
ISIS will torture people in the streets, cartels will do similar, but nothing really strikes fear into the people like the public rape of your family members.
It's not just you that's on the line, it's not just death you have to deal with, getting your mind broke gets added on top of that.
The thought of that alone would scare people away en masse.
It still has its flaws, you could easily throw an STD into the mix and there goes a lot of soldiers (I doubt they use protection).
There's also various viruses and chemical radiation, there are plenty of new ways to stop it.
The old ways would have been public castration, perhaps with a side of dogs feasting on your lower parts.
Either way works really, I wonder what will be done... if anything at all.