HN submissions are URL based, but display of submissions are based on a
combination of factors including up-votes, flags and time since
submitted. As the name "Hacker News" (or "Startup News") implies, the
goal is collecting "news" articles rather than "classics" or even
"topics" and of course, this design splits discussions amongst related
submissions.

For the moment, let's just assume a "merge" feature exists. How would a
merged thread be handled for the sake of display? How would up-votes be
handled? How would flags be handled? --We've got a tough problems right
there, but we've skipped over the most blatant problems...

Who decides a merge?

Can merging be abused?

What granularity of merging is desired? (Do you want everything
regarding recent problem of the AirBnB customer to be in a single
submission, or do you want absolutely everything regarding AirBnB in
total to be in a single submission?)

Who decides the granularity?

The existing duplicate checking is based entirely on the given URL of a
submission, so it is easily abused, and knowingly flawed, but it's still
far better than nothing. Identifying duplicates, and more relevant to
this discussion, similarities, would require content analysis of the
submitted URLs. It is feasible, but it is not easy. None the less, a
solid content analysis algorithm would take care of the "who" and
"abuse" problems, as well as allow some degree of configuration on the
granularity.

Using your example ( http://news.ycombinator.com/item?id=2822080 ):

Assuming the seven submissions of the "G-Man" video are hosted at
different URLs (duplicate videos on youtube), really serious content
analysis would require downloading and analyzing all seven video files.
Oh wait, the asshats at google (and every other video site) refuse to
simply give you a link to the video file(s), so you have to do your own
parsing, processing and often de-flash-ing of their pages to figure out
the file download URL. And as soon as you have it working, they will
change how they present video to break your code (see
http://savevideo.me and similar browser addons for reference).

The other problem with content analysis on HN is the server would melt
into a pile of slag. As HN exists, a single FreeBSD box (AFAIK), it
would never be able to handle the load of content analysis.

Colin, your manual cross referencing is helpful, and I do appreciate it,
but I believe it is a waste of your skill and time. Yes, I remember you
have some code to somewhat automate it, but the reaction from the last
time you ran it was not the most positive. We can't treat HN as our
private play pen; for users it's a utility, but for PG/YC it is a way to
source hackers to fund and a way to promote news stories about YC funded
companies. --I don't mean it in a bad way, instead, it's just the well
known facts/benefits about HN. HN serves different purposes for
different people. I've always admired how PG and RTM consistently try to
sell shovels in a gold rush (viaweb, ...), and HN is simply their newest
type of shovel. ;)

Sadly, the phrase, "All press is good press," should now come to mind.
In other words, consolidating submitted stories into merged submissions
is actually disadvantageous to PG, YC, and the YC funded founders. You
are asking them to get less valuable press. Everyone who understands how
AirBnB works has been expecting a catastrophe like this to happen
eventually. BUT AirBnB making it onto the front page of the Financial
Times is extremely good for their business, even with "bad" press like
this.

Though many find "endless repetition" of similar submissions annoying,
the people in control of HN/YC and the founders of YC funded
companies understand it is VERY advantageous for them. Given you are
asking to "harm" the powers that be here on HN, you can be reasonably
well assured that we're stuck with endless repetition. This is most
likely the reason why you (currently) have 218 "Do Nothing" votes, and
worse, 27 "Go away. Just Go Away" votes.

It might be a great idea for HN users, but HN is the wrong place of this
particular great idea.