Yeah, it can get pretty nasty on both sides. People who don't warn are jerks, just like people who knowingly go read things they know will trigger them and then complain about it are stupid. As well, there's a difference between "I hate XXX" versus "I hate everyone who likes XXX." But people saying the former tend to get jumped on since people assume they're saying the latter. I think OP's thing is that both sides should be allowed to speak and neither one should get away with trying to force the other to shut up.