It's a reliable way to get inaccurate information into your idea of what's going on.
It gives people a good reason to hate you. Even if you think they already hate you for bad reasons, adding good reasons will make things worse.
Torture means people aren't going to want to surrender to you.
It's evil. I don't know whether evil is a separate feature on top of spreading misery while doing something that undercuts anything legitimate you're trying to accomplish, but it might be.