On the other hand, I get the concern of regulating trolls and spammers. Unfortunately, I think humans being humans, they will not use a ban option for those purposes, and will ban people they merely disagree with, or whose tone they do not like. It's like the Reddit down vote. It was never supposed to mean 'click if you disagree with the comment above you' but that is EXACTLY what it means in reality.

Just to be clear, this block would be across all of the user's posts, not just that post alone. That's why I wonder if it would be self-correcting in action. If you block a lot of commenters, you simply might not get much participation on your posts, both because you block them, and because others might stay away. -I know that I would be less inclined to comment when I know the author blocks a lot of users.

I think your 'turning on a downvote' idea is interesting, but I'm not sure that it wouldn't be abused any less. Is it better that the author need the community's approval?

At any rate, I am on the fence with this. I'd almost like to see it in action just because I don't know if it would work or not. Even so, I don't think we'd see much use of it right now.

Thanks for the ideas.