Daniel, I know you mean well, but your suggestion of "flag sparingly" is
only useful some of the time, and there is code in place to handle those
who flag excessively. As always, there's more to it than meets the eye.

There is a great deal of "secret sauce" running on HN, and to prevent
adversaries from abusing HN for their own gain, PG deliberately does
not publicly divulge how a lot of things work. [1] You would need to
have either a deep fascination with discussion forums, or far too much
free time (probably both) to figure out some of the non-public details
of how HN really works. If one really does their homework well and
figures out some of the details, hopefully they have enough respect for
PG, YC and all of the folks using HN to not abuse or divulge what they
learn.

Though the precise details are not public information, pg has publicly
stated that he does have some form of (vote/flag) "ring detection"
running here on HN to thwart group and/or multi-account manipulation.
[2] Since the details are not public, there is really no way to know
how effective the ring detection is, but suffice to say, if it wasn't an
improvement, it wouldn't exist.

When it comes to flagging and up-voting of submissions, the publicly
described logic is both clever and fascinating. If you flag heavily
up-voted submissions, your flags count less. Similarly, if you flag too
many things (and most likely, too quickly), your flags count less. In other
words, there are thresholds employed. [3,4]

When it comes to flagging comments, I can't recall seeing any mention of
how the comment flags are handled, and worse, there's nothing in my
notes about it. Considering the potential for abuse, I doubt PG will
ever give vague details about it. Spam comments are an interesting
problem, and it's very difficult to solve. Allowing users to flag
comments is one way to handle it, but divulging the details would most
likely reduce the effectiveness of the counter-measures.

There is still one place on HN where doing a lot of flagging and
up-voting of submissions is both useful and beneficial to HN as a whole,
namely, on the "new" page: https://news.ycombinator.com/newest

I'm sure many people appreciate the high signal to noise ratio here on
HN, and would rather avoid the more noisy /newest page. None the less,
people putting in some time to both flag spam and give up-votes to new
submissions is what keeps the high signal to noise on the front page.

Yes, even if you're just flagging spam on the /newest page, you can
still trigger the "excessive flagger" threshold, and the result is
(was?) the "flag" links disappear. I had it happen to me once a long
time ago, but since then, I believe the system was changed to simply not
count the flags once a user has passed the threshold value. I would bet
a human being (pg or a moderator) looks at any account that flags too
much to determine if the account should be banned, hell banned, deleted,
or whatever. If they see that you're really just trying to flag the
endless spam submissions, they probably just quietly appreciate your
efforts. I've never received a gilded thank you note for flagging spam
submissions, and I don't expect to get one, but I'm sure everyone who
likes the high signal to noise ratio around here appreciates it.

NOTE: Though the references below are from PG himself, it's entirely
possible that he's changed his mind, and his code, since they were
originally posted.

[1] https://news.ycombinator.com/item?id=830838

[2] https://news.ycombinator.com/item?id=3354900

[3] https://news.ycombinator.com/item?id=830485

[4] https://news.ycombinator.com/item?id=830531