You sure it isn't just the limitations of the medium? Threaded discussion lends itself to longer messages. And since the author of the post isn't guaranteed to

You sure it isn't just the limitations of the medium? Threaded discussion lends itself to longer messages. And since the author of the post isn't guaranteed to be here, we can't ask questions and expect an answer. If we were on IRC, I'd expect more of a two-way conversation. Instead we have people sharing their comments (Hacker News often reminds me of blog comments.)