A few thoughts. I think writers and other commentators need to fight back too. Why wouldn’t we be wise to self-police online? Why wait for platform leaders?
I think if you ask for civility, you are more likely to get it. We shy away instead. Point is not to avoid the comments but to engage with some of them — not the worst ones but the ones where one can detect hope. I have done this several times and I actually feel better.
And, another approach, write about the importance of civil engagement — as you have done. The more we write about it and role model it, the better off we will be. And, call out politicians whose rhetoric is way over the top and offensive.
Here’s a piece I wrote on this very topic. Hope is helps too. http://www.huffingtonpost.com/karen-gross/what-makes-a-democracy-wo_b_8992632.html.