The high impact of a few loose screws

IMO there are more than a few

Good point. I think one of the things that social media has done is give the nutjobs on all sides a huge, loud megaphone wildly out of proportion to their numbers in society.

I follow a congressperson in FB. This person (OK their staff) posts pretty much daily, and the posts generate about 50-75 comments that are generally split 75% negative, 25% positive. What I've noticed over the course of time is that the same 10 or so people post every time, and in some cases just copy/paste their comment from the previous post.

Very true, Nina. The few can give the impression that they are the many, simply because they are loud and can say things they never would in person. It is akin to a mob, where otherwise reasonable people can get caught up in a moment.