The lack of any real community at many places that have comment threads is one of the big problems imo, which would create some of the "incentive to behave" and "semblance of real identity" (even if "real" is pseudonymous, it's real within a community). And it's pretty hard to build a community around one person's personal blog, unless it's a very small one (their circle of personal friends).

That's one reason I think the HN comments are often better than the comments on the posts HN links to. It's also one reason I think there are significant downsides to the de-centralization of tech blogging: where in 1998 someone with an article to post would have posted it within a community (say, submitted it to Kuro5hin, or Metafilter), today they often post it on their personal blog. There are definite pros to the ability of anyone to publish anywhere, but I think it makes everything more disjointed on the discussions.