<personal bias, no time to research this for sure> The extremists weren't going to be swayed anyway by people arguing with them, or even ridiculing them on the internet. If anything, the focused subreddit with its own moderation team can create extra legitimacy by voting down arguments and dissent, or deleting them entirely. Spend some time on thedonald, and see how much actual useful debate there is on the posts attacking Hillary's body.

It's the large, non-participatory cohort of people who may have never read the comments that are being helped by banning these groups, because these behaviors seem less 'normal' and 'legitimate' if you don't see them, especially if you're not exposed to them as jokes and pithy quotes.

Some of the coontown people will slink off to the KKK blogosphere and private message boards, but my point is that many of those with only mild biases won't, and so will lose the chance to be radicalized.

Arguments with extremists aren't for the benefit of the extremists; they're for the benefit of onlookers who perhaps haven't considered counterpoints.

And if a community deletes or down-votes dissent: well, that happens but it also becomes a matter of public record and can also inform. Case in point: the moderation of /r/politics.

Nothing is served by "saving" Joe User from being exposed to unpleasant speech in an open forum, due to the fear that he might be adversely affected or even damaged by the experience. This is anti-vaxxer logic, on a meme level.

I think you're really idealizing these subreddits here. The way reddit works, the downvoting of dissent will never be seen, that's the problem. (Generally a pro of reddit, but not in this case). Dissent will get sorted out of the comments section by default, and the arguer banned. The nature of these extremist groups is not to have an open forum for discussion.

There is not a public record to be examined and ruminated on, on the contrary it's a situation where you can go and see "oh 151,400 subscribers to fatpeoplehate, this is normal behavior", or (more likely) people who never view comments will just start to see jokes about killing the obese on their front page feed.

There's a difference between 'saving people from unpleasant speech' and providing an echo chamber to hate speech along side the company's incredibly popular other content.

I don't see the connection to antivaxxer logic, but I'll give you the benefit of the doubt there?

Just to be clear I'm not advocating that we ban all 'unpleasant speech' from the internet, but I do think siloing it off so you really have to be looking for it works, and that there's significant evidence to back that up.

In reddit's case in particular, many of the banned subreddits were using smart tactics like brigading and vote manipulation to amplify their numbers, and push the 'this is normal' message even further, although that's somewhat orthogonal to what we're arguing about.

Reddit isn't completely a black box: subs such as /r/undelete and /r/longtail track deleted threads, and deleted comments can be reviewed ( https://www.reddit.com/r/howto/comments/5en53l/how_to_see_de... ). Additionally, the disparity between upvotes and comments -- especially for threads upvoted far more than their peers -- can indicate when voting shenanigans are taking place.

A casual visitor wasn't terribly likely to see counterpoints and ridicule on those parts of Reddit, though, because they banned them with an iron fist. FPH in particular was very consistent in banning anyone who empathised with its targets or questioned any of its dehumanization or its tactics. It was essentially a safe space for hate.