Now that's what I call a loaded question.

You're right, they technically don't. But they ban everything that can be even remotely interpreted as "offensive". To give you one example, I got banned for pointing out the appeal to nature fallacy. I've said that rape and murder is technically natural and yet it's not socially acceptable. Literally just that. Nothing less, nothing more. But someone either misinterpreted that simple sentence or found it offensive because of the context of the conversation, and thus I got banned.