Thanks for the input. Great points.

The flagging system on HN shares some similar aspects to the ones you
mentioned (congrats on 250K active users!), but in many ways, it's a
completely different system and has a slightly different intent. It only
takes a few flags from established users for new submission to be marked
[dead] and invisible to most people, save those who have "show dead"
enabled in their profile. In this sense, HN flagging is designed to
crowd-source the task of removing spam, abuse, and off-topic material
from the site.

Essentially, flagging is community cleanup, and it's the reason why the
flag link is so prominent... --You probably remember when the front page
didn't have flag links. For a long time, only the /newest page had
easily accessible 'flag' links. The change of putting 'flag' links on
the front page was made because junk kept getting up-voted onto the
front page, and since most people didn't know how to flag (by visiting
the 'link' link), the result was discussions about inappropriateness.

Flags on HN work differently than what you described. If
you flag something and it gets flagged by enough other people (tempered
by anti-abuse ring flag/vote detection) to be marked [dead], then it was
a "good" flag. Similarly, if you flag something and not enough others
flag it to become [dead], then it was a "bad" flag. The more "good"
flags you make, the more weight is given to them, and of course, the
more "bad" flags you make, the less weight is given to them.

(NOTE: Above I'm paraphrasing something pg posted eons ago, and I can't
find the link, so I might not have the details perfect, and the details
may have changed since then.)

Also, flags reduce rank in the HN sorting, but exactly how flags reduce
rank is undisclosed (contra-factor --see pg's second post here):

https://news.ycombinator.com/item?id=1781417

If you flag something, and it does not go [dead], your flag still has
some effect, but the details of whether said flag is "good" or "bad" are
unknown. All I can say for sure is if something is highly up-voted, and
also heavily flagged (i.e. controversial), it sinks down the ranking
and off the front page very quickly even if it is never marked [dead].

It's a very clever design, reduces the workload on mods/admins, and
enables you to do some other interesting stuff...

Most of the details are not public, but I'd bet PG uses the good/bad
ratio to determine things like the per-user threshold value where
flagging is disabled for a user. I also suspect it would take some other
count and/or good/bad threshold of flags per-submission or per-post for
admins/moderators to be bothered with any kind of alert. Why bother the
mods/admin when enough known-good users have flagged it to [dead]?
These two points are pure speculation on my part, but having the
good/bad flag ratio per-user allows you to lighten the workload on
mods/admins.

Of course, pg not elaborate on the anti-abuse code, and I sincerely
doubt he will neither confirm nor deny anything I've said publicly
because he just can't without jeopardizing the effectiveness of his
anti-abuse code. (Yes, I'm intentionally giving him an out).

On the other hand, having PG provide a bit more instruction on what he
wants flagged could be really useful to the users watching the /newest
queue, prevent well-intentioned folks from unnecessarily triggering the
abusive-flagger threshold, and at the same time, help improve the
quality on HN.