This story has had major threads on HN, including on the front page right now [1]. Our interest is not in quellage but in keeping the front page substantive, i.e. keeping HN HN.
Big drama always brings many copycat posts and follow-ups. Most need to be treated as duplicates or drama will fill the front page, which is not what HN is for. Where to draw the line? Our answer is, have a major thread on (hopefully) the most substantive version of a story, plus a new thread when there is significant new information [2]. That's the best way we know of to balance the different factors, though we're open to a better way if anyone suggests it.
It's true that it's common for a user to miss earlier discussions, as you mention, but that's a problem with HN in general. No one sees all the threads. We try to point to previous discussions when we notice them, and many HN users helpfully do so as well (greenyoda and ColinWright practically deserve medals for it).
1. https://news.ycombinator.com/item?id=9840805
2. https://news.ycombinator.com/item?id=9827903