I think I may have said this before so maybe I repeat myself, but IMO, online communities are going to be prone to extremism.
30 years ago, if you thought dressing up as Daffy Duck and making love with someone dressed as Bugs Bunny would be the hottest thing ever, you’d be highly unlikely to ever find someone in your town that had a similar outlook. You’d realize that your opinion was in the extreme minority and it would quietly stay in your head. Most everyone else in your circle/the local area would trend towards the moderate as that is what you would be exposed to. One could argue whether this is good or bad.
Today though, you can easily go online and connect to lots and lots of people with the same extreme minority opinion you have. Those folks will not only tend to then cluster together, but it will then start to seem to them that their extreme minority opinion isn’t actually all that rare because they managed to connect with so many others through cyberspace. So then it starts to be put out there more and more and become more accessible as an idea at all. And maybe folks who wouldn’t have even had any idea such a thing existed suddenly start nibbling on the edges and dipping their feet in. So over time, extreme minority ideas can start to work their way into the mainstream.
This doesn’t always have to be a bad thing. It’s really the entire idea behind spreading democracy by exposing the oppressed to it. The hope is that by increasing exposure to good ideas that have been repressed in an area, the idea can become more mainstream and accepted or desired.
But we certainly see the downsides as well.
Just as Twitter has a reputation now of being dominated by “right” leaning views, it’s pretty clear that Reddit leans quite “left”. As groups cluster, views tend to become more and more extreme as the echo chamber reinforces.