EDIT: Thank you for your response, dang. Hacker News is a special place, which is why we have responded so strongly to today's events - I apologize if the tone above came off as less-than-civil. I (and it seems, many others) look forward to hearing more about the 'dupe' article others have linked to below. It was only upon seeing the article marked as a dupe after seeing the previous flagged out of existence that it began to feel like more than just a user-initiated action, so I am sure further information on the mod-initiated actions will put these fears to rest.
Here's one tip for you guys, from years-long, world-weary experience: if you're coming up with sensational explanations in breathless excitement, it's almost certainly untrue.
Edit: ok, here's what happened. Users flagged https://news.ycombinator.com/item?id=27394925. When you see [flagged] on a submission, you should assume users flagged it because with rare exceptions, that's always why.
A moderator saw that, but didn't look very closely and thought "yeah that's probably garden-variety controversy/drama" and left the flags on. No moderator saw any of the other posts until I woke up, turned on HN, and—surprise!—saw the latest $outrage.
Software marked https://news.ycombinator.com/item?id=27395028 a dupe for the rather esoteric reasons explained here: https://news.ycombinator.com/item?id=27397622. After that, the current post got upvoted to the front page, where it remains.
In other words, nothing was co-ordinated and the dots weren't connected. This was just the usual stochastic churn that generates HN. Most days it generates the HN you're used to and some days (quite a few days actually) it generates the next outlier, but that's how stochastics work, yes? If you're a boat on a choppy sea, sometimes some waves slosh into the boat. If you're a wiggly graph, sometimes the graph goes above a line.
If I put myself in suspicious shoes, I can come up with objections to the above, but I can also answer them pretty simply: this entire thing was a combo of two data points, one borderline human error [1] and one software false positive. We don't know how to make software that doesn't do false positives and we don't know how to make humans that don't do errors. And we don't know how to make those things not happen at the same time sometimes. This is what imperfect systems do, so it's not clear to me what needs changing. If you think something needs changing, I'm happy to hear it, but please make it obvious how you're not asking for a perfect system, because I'm afraid that's not an option.
[1] I will stick up for my teammate and say that this point is arguable; I might well have made the same call and it's far from obvious that it was the wrong call at the time. But we don't need that for this particular answer, so I'll let that bit go.
I apologize if the questions of myself and other users on this site today has set you on edge - and I am sure that today, in public and in private, you have seen many ugly things that the majority of us do not, and you reasonably draw a trend-line. I believe that you should extend the same charity of trend-spotting in the other direction.
We live in tumultuous times, and the speed at which the ratchet is moving seems to be ever-increasing. There are significant concerns, as I know you know, about censorship abroad, and also at home in various western countries. I believe the overwhelming outpouring you have seen today has been in response to one undeniable fact -- that even a genuine accident on the part of some engineer somewhere could apply CCP (or any country's ruling party) censorship globally is a line in the sand that many did not realize had been already been crossed.
Whether accidental or intentional, this is a watershed moment in the debate over censorship and freedom. It seems likely there are many more such errors in configuration actively deployed right now. That we have no way of knowing what, or how many such incidents there are is an existential threat to non-authoritarian systems of governance across the globe.
To see something that seemed unthinkable even a few months ago - that Tank Man could be censored in western countries on the anniversary in remembrance of the struggles he literally stood for - crossed a threshold for me in terms of what I believed could be possible more broadly. To see the extremely reasonable discussion around it disappear from hacker news, and stay dead for hours (I note that both the inappropriately-flagged article and the accidentally-marked-as-dupe article both still maintain those statuses at the time of this writing [EDIT: The flagged article's status was changed a few minutes after. Thank you, dang. Doing so does not mean you are re-writing history, and we appreciate it]) made it feel like it had encroached even closer to home than I had suspected.
It made it feel like perhaps I'd been even more naive than I had ever imagined. I'm sure you must feel the same way, after some of the more hateful things I'm sure you heard today.
All of this is to say that I treasure the community that you have played the single largest role in shaping, and your explanations have completely satisfied me.
I apologize for the way your day turned out, and any negative ways in which I have contributed towards that.