I don't think the intent of posting on a visible, high traffic public space is to only offend the onlookers but to also incite outrage that cascades into other

I don't think the intent of posting on a visible, high traffic public space is to only offend the onlookers but to also incite outrage that cascades into other communication channels. Free attention from vitriolic strangers stemming almost solely from lacking self control to the point of expressing frustrated opinions is all they could ever ask for, at a minimum.