I'm not sure that we can provably say that they LEAD to crimes. I think there's a strong case to be made that people interested in carrying out these crimes find like minded people online and engage in meme culture. You can probably make a good case that things like 8chan encourage copy-cat elements in these attacks.

I'm just not quite sure the case has been convincingly made that internet cess pools generate crime that would't otherwise happen. I could probably be convinced otherwise, but I'm not sure.