Thanks for explaining. I think it's important to note that any perceived-consensus in some random-thread doesn't mean much - it's not necessarily a real consensus or conclusion, and in any case the actual site managers have their own ideas about how things should work. (And, while they clearly welcome some input, they also seem to frown upon most meta-discussion, complaint threads, coordinated-voting-pacts, and lobbying-polls.)
Personally, the occasional posts of Wikipedia articles and PG essays (even repeats when related to current topics) are valuable to me. I think it'd be a misuse of the 'flag' to suppress these. Of course anyone is free to misuse their click-power like that... I just don't want anyone to misleadingly claim that's a consensus norm, with the vague assertion "we already decided this". That seems like a rhetorical trick.
Unfortunately, this was all discussed in an ad hoc fashion in comments to random stories but I'll do my best to find it.
time passes
First, https://news.ycombinator.com/user?id=whoishiring is the bot that submits the "Who is hiring?" posts. It started a few years ago as you can see by the registration date for this user. The problem was that these posts generate a lot of upvotes, and people started trying to beat each other to the punch to try to get more karma points. The problem came to a head when multiple "Who is hiring?" posts made it to the front page, which has the obvious negative consequences.
I just spent about 30 minutes searching for the other two discussions and cannot find them (hnsearch, Google, and my own story upvotes proved unhelpful). Best I can offer is this: about two years ago, IIRC, there was a trend to link directly to Wikipedia. The front page was filled with random posts on there, like the one about the illegal numbers. Wikipedia is great, but often times it was not clear why a post was relevant to HN. The conclusion of the discussion was that we shouldn't post Wikipedia articles directly and the trend died down. @gojomo, I wager you have been here long enough to remember this trend, and I'm sure you noticed that one day it stopped. That's probably the best proof I can offer on this point.
Something similar happened with pg's essays. Every time he posted one, it would show up on the front page. At that point someone posted a master submission, linking to all of them, and in the discussion there was agreement that since pg is so well known here and his essays are so closely watched that it is taking away from other stories to post the content that almost everyone will discover anyway. Additionally, this once again lead to karma farming by multiple people trying to post the same essay as early as possible. Interestingly enough, I just tried posting the link to all the essays and the duplicate matching engine let it through, so I wonder what happened to that post (and/or my memory of it). In either case, it looks like this trend is also starting to slowly come back.
Once again, I really wish I could find these discussions and/or compel the site admins to clarify some of these points in the guidelines. Alas, I do deserve the downvotes in my original post for not including any references.