"Is that a reason to hate on them?" --> Many women don't hate incels, but they consider them dangerous. And people avoid potentially dangerous things. There is a difference between hate and avoid potential danger.

And sure, maybe they don't really agree with Elliot Roger and only said so at their forums (with a silent majority), but the fact is that Elliot's message was left unchallenged at those forums. So women distrust them and see them as potentially dangerous.

I don't hate fire, but I won't get to close to it to avoid get burned. I don't hate incels, but I would keep my distance for the same reason. I'm sure I'm not the only one that see it like this.