Reddit reviews This Is Why We Can't Have Nice Things: Mapping the Relationship between Online Trolling and Mainstream Culture (The MIT Press)

Answer:

Summarizing sites like 4chan in a reddit post is really hard.

"This Is Why We Can't Have Nice Things" is a pretty fantastic gonzo-journalism/ethnography about online trolling culture circa 2012 that dives deep into the culture of 4chan users and other outlines of "troll culture".

I recommend it because I think it gives a better answer about the essence of those sites than is possible in this thread.

But to attempt to provide something in the way of an answer, I'll summarize the book's ultimate hypothesis:

• Many of the most prominent posters to 4chan (and other similar sites, but I'm going to call them all "4chan" for ease of writing) compartmentalize their lives in "online troll" and "offline person". This allows them the ability to act in an anti-social or even sociopathic way online without suffering cognitive dissonance.
  
• In the author's assessment, these online trolls put on the "Mask" of the cross-cultural culture hero "The Trickster". The Trickster has different forms in different cultures, but one of the common cross-cultural similarities in Trickster stories is that the Trickster breaks cultural norms and taboos to reveal something.
  
• When viewed through this lens, online trolling can often be see as a way to reveal something. Through trolling, the victim is forced to confront their assumptions and values about a situation. The troll is asking them to see it in a new light, often to simply revel in the absurdity of existence in an Existential or even Nihilistic philosophical lens.
  
• Other times, trolling victims are chosen precisely because they build themselves up as an authority, or some other type of important person or authority figure. Cross-Culturally, one of The Trickster's roles is to humble the powerful or arrogant. This type of trolling will often focus on the contradictions in the victims stances. The Trickster reveals.
  
• All of this is amoral and largely unethical. The author struggles with making a value judgement around online trolling. Much of it is very cruel. But it intentionally exists outside of cultural norms and accepted behavior.

Yeah sure man. I'm on mobile but the TL;DR of what I have so far is that unlike previously, the Internet as a "third place" can be accessed by everyone (unlike, say, a bar) and from around the world.

The use of content aggregators like Reddit that pull from content-focused communities (4chan, for example, has zero emphasis on content creators and has value only in content created and what is contributed to the conversation) result in an influx of people coming into those sites who, abandoning tradition, brought their baggage with them from other sites. Whether they tried to turn 4chan into something it wasn't didn't matter, because that was the perception its users had. Furthermore, the influx of users from other sites did exist, and provably, because the site went from hating all the others, to suddenly being okay with them (and openly admitting to using them no longer disqualified you from conversation).

I'm not going to go into a screed on 4chan, but it's really sad what happened to the culture as a whole; the effect it's had on Internet culture- and IRL culture, particularly in America, as well- is incalculable (but large). Take a look at Whitney Phillips' book "This is Why We Can't Have Nice Things" (it's online, on JSTOR if you have access) and where she talks a lot about the culture of /b/ from 2007-2014, and then go look at /b/ now- it's all porn and narcissistic threads (rate me! Meetup thread? purely porn threads, etc.). My operating theory is that narcissism, a focus on the person and on conformity, was a huge part of the Internet- but except for conformity (and even then not so much due to the source of the userbase as a counterculture), 4chan lacked all of those due to its forced anonymity.

It's kind of like the white supremacists say about how multiculturalism is bad. I don't know or care to offer an opinion on that IRL, but I think it's true within the lens of the Internet. (I'm not a supremacist of any kind, just borrowing the metaphor)

I'm glossing over a lot, and this is a very long TL;DR, but bear in mind that an abstract (a TLDR in essence) is about a page long.

TL;DR of the TL;DR (if this interests you, just read the whole comment FFS): Internet forums are the new "third place." Content aggregators focus more on people than on the creation of content; as a result people look further for things to bring to the table to be the first to hop on a trend. Unfortunately this means that once-unique cultures and Internet places are brought into the mainstream, and those places are not only no longer special- but they get people from outside diluting the culture further.

Since people seem to be throwing out book recommendations, I'll add This Is Why We Can't Have Nice Things. It's still on my "to read" pile, but it seems to tackle the whys and wherefores of trolling head-on.