I think your comment is gold. Because I've been also thinking about the construction, organization, and mechanism of online communities in general, most of my comments were posted to another community, but I posted some related comments on Hacker News as well. I'll start dumping comments as well, I hope you find them interesting. Feedback is appreciated.

1. First, I've been observing various online trolling culture and fringe reactionary political movements for a few years. Mostly 4chan, but I think it applies to the web in general. While I don't agree with their intentions or motivations, but I found it's an extremely interesting phenomenon and pretty post-modernist in itself.

* The cyclist behind an anti-cyclist Facebook group

https://news.ycombinator.com/item?id=17731220

* Recommended comments (read the link below before you continue):

https://news.ycombinator.com/item?id=17731914

Here's a story: a biking hobbyist used his spare time and launched an influential anti-bike movement on Facebook. He posted numerous sensationalized commentaries, posters and memes to demonize bikers, including the various "data" and "charts" for the "bikes are a great threat of traffic order" propaganda, and occasionally advocated violence towards bikers in forms of half-jokes. He also proposed political reforms to introduce restrictive and/or discriminatory traffic laws for bikers. Soon, his campaign has gone viral and attracted a large number of supporters who drive cars. Well, not all bikers follow the traffic rules and some problems surely exist, but they are only as bad as the average day-to-day traffic and usually not seen as something people need to act upon, but this campaign exaggerates it, radicalized it and polarized the issue and created lot of hate. What is his intention then? His only intention is laughing at this fact: he was able to manipulate the car drivers easily and even create a raged populist political movement with a mere keyboard.

We hardly know who's behind the populist political movements online, but this is a well-documented case, and I believe it can be a representative sample which largely reflects the origin, emotions and motivation of the 4chan-like "for-the-lulz" trolling culture. Also, I can immediately point out the similarities to the populist reactionary political movements: the nationalism propaganda used many of the tactics the biking troll has used. Also, Russia is accused by the media to create an army of bots on social media, such as pro-LGBT, anti-LGBT, pro-life, pro-choice, religion fundamentalism, atheism, nationalistic, liberal, etc, with the intention of creating polarized argument and social conflicts in the United State.

On the other hand, the "for-the-lulz" trolling culture itself, even can be used as propaganda, is not propaganda in itself. It is a form of complicated web culture. It's basic definition is "doing some pointless activities to make others to suffer, and laugh at it", but it stands for a lot of things. It has a reactionary, or anti-establishment element, as previously mentioned, but it also includes: (1) cultural jamming, similar to the 70s counter-cultural movement (see those hoaxes in Fight Club), (2) It understands the art of exploiting a vulnerability in the system for one's own advantage, similar to parts of the hacker culture, (3) Also, it has a somewhat nihilist, post-modernist component, sometimes artistic (The Game was popular on early 4chan: once you remember playing it, you lose it), and (4), it reflects the worrying, helplessness and alienating aspects of modern life, and as an entertainment against them using humor and hate, then finally (5) a populist movement. It's core logic is: everyone, look how evil/degenerate this thing/person is, the justice needs to be done! Sometimes, it can be a legitimate popular movement and serve the right purpose, e.g. Occupy Movement, but other times, it's just a bunch of angry mobs lynching people. For example, a list of people on Encyclopedia Dramatica.

Especially, when I grasped these points, I found things went pretty stupid when, for example, the mainstream media started reporting Pepe the Frog as a hate symbol in 2016. Yes, it has connections to reactionary political movements, but itself is only a symbol of the trolling cultural. When the media reports it, it actually gives it a platform of exposure, and encouraged trolls to use it as a genuinely political symbol, and personally I think it makes the issue worse.

What I'm trying to say is, to solve problems like this, we must study and understand the entire machinery of it, including the underlying social-economical basis of this conflict using sociology and psychology, and to provide social solutions to the problem. However, the only proposal the mainstream media (or us, as online members of online communities) has right now is "Twitter and Facebook should ban hate speech", or "we should not feed the trolls", which hardly touches deeper problems.

If you want to understand more about the trolling culture and its mechanism, I recommend "This Is Why We Can't Have Nice Things: Mapping the Relationship between Online Trolling and Mainstream Culture", by Whitney Phillips, published by The MIT Press.

Here's are related comments on this issue I have posted before,

* Twitter has barred hundreds of accounts for posing as liberal activists

My comment: https://news.ycombinator.com/item?id=18239216

* RIP Culture War Thread

My comment: https://news.ycombinator.com/item?id=19231994

This one is mostly a repetition, but it includes one more book recommendation. I also recommend to read the original web article. It has covered a lot of related discussion.

2. I was also trying to characterize online communities in terms of its medium, feedback mechanisms, and filtering mechanism. A online platform has a lot of content, but you only see a subset of content. The filtering mechanism determines which subset it is. We could say, the first generation of online community is mailing list, Usenet newsgroups, and web forums. It only has a simple filtering mechanism: grouping the content by topics, and a kill file (a people/keyword blacklist, sometime shared). It works relatively well, and has the advantage of producing diverse topics, free-flowing discussions, but there's nothing to stop low-quality discussion, so a good signal-to-noise radio must be carefully maintained. Another problem is the lack of feedback: when nobody reply for post, it means five different possibilities, see Warnock's dilemma (https://en.wikipedia.org/wiki/Warnock%27s_dilemma). Another important issue is: the entire forum basically stops scaling when the number of users exceeds 10,000 or so. The information is too much to handle for any individual.

Platforms like Reddit or Hacker News can be seen as the second generation, it introduced voting as a feedback mechanism, which simultaneously (partially) solves the problems of content recommendations, restriction of low-quality content, and scaling. The "karma" system of Slashdot also counts, but it has a innovative "community moderation", so I guess it's 2.5 generation. Anyway, overall, its usefulness of voting as feedback is great and now becomes an integral part of many communities, but not without its own problem. Voting creates a strong incentive for people to collect upvote. People may stop talking about insightful contrarian views, which otherwise can generate an intellectual interesting discussion in a newsgroup. Also, voting seems to be more suitable for link/media recommendations, but less suitable for discussions. Many subreddits has thousands of votes for links but a single digit of comment.

Finally, ~2007, here comes the social media. Social media is unique because it leveraged the underlying human social network as a means of the filtering mechanism, and has a somewhat "decentralized" model of publishing. Unlike a forum where everyone post to a single directory, on Twitter, you post to your own account, and others can simply follow a number of people, then interesting posts simply circulate by itself. The system is highly effective, I love social media. Unfortunately, problems. First, the content has to be short, no long discussion is possible. This is usually not a problem, but the social media has slowly killed most forums in the process and became the center of the web, forcing people to use for discussion, although the social media is an awful platform for this purpose. Its structure is conversational, posts don't have a single thread, but a dozen of microthread. A replies to B, but this reply is usually ignored by C, which may have crucial context. Furthermore, the volatile nature causes many problems, A mentioned X 3 hours ago, and now X is missed by most readers. Or, A posted X and Y, but often only a single X/Y is seen by other readers, while the other one has important context. Also, the social media has the strongest filtering bubble effect compared to all platform, which may create an echo chamber, increase political polarization among other effects.

But think about it. Voting was invented by Reddit in ~2002, social media is a thing from 2007. Can we design a new generation of communities with innovation? A better alternative "filtering mechanism"?

3. I noticed a lot of online communities seems to go downhill. What is going? I have a comment.

https://news.ycombinator.com/item?id=19958700