One thing I don't get is why people comment on hacker news and not at the actual blog post??? Sure it gives the link more points and push it to the top which will generate more traffic, but wouldn't it be more helpful if this comment was at the actual article so others reading it can benefit from it? Just a thought.
But seriously, mostly we care more about talking to the HN community than we do about adding value to your article. When you say "more helpful," you mean more helpful to you and your readers. "More helpful" to me might mean more accessible to Hacker News.
Get used to this. The more your startup gets covered, the less control you'll have over the conversation.
There are advantages to doing it on the blog post itself, too. People who find the blog post a year from now will see comments on the blog post itself, most blog comment software at least supports more markup than just paragraphs and italics, the blog author is more likely to read it, etc.
not the sense of community sadly. You want some form of aggregator that merges comments on here/digg/reddit with your blog.