Or just turn off comments altogether and let people comment on HN (et al). This happens inevitably, right? Many times the comment thread for an article is actually longer and more rich here than on the source website itself.
If bloggers want the discussion to happen on their blogs and not on HN or reddit, then they really need to offer something better than HN or reddit. Hell if you can't even do threaded comments or something similar to make it easier to follow the flow of discussion, it is obvious to me that you don't care too much about getting comments.
