I think it's especially hard on HN due to the nature of the site. Since HN is a site dedicated to discussion, it becomes important to ensure that open conversations are happening. Strong opinions shouldn't be banned just because they get a little hostile, and weak opinions shouldn't be banned just because they're a little fluffy. There's such a huge gray area that it's an impossibly difficult problem.<p>Contrast this with Engadget, who can enforce discussion that aligns with whatever site policies they choose to adapt. Or  you can take this even further, like on my blog, where openness means nothing and I can just delete anything that's not a question or an anecdote that adds to what I've written.<p>In an open discussion forum, your biggest problem will be always be open discussion.