Again and again, research shows that online hostility is not a result of echo chambers, but of giving aggressive people a channel to be hostile to everyone who would normally avoid them
The problem with unmoderated online spaces is that a few people will always ruin them. Most conflicts between Reddit can be traced to a handful of active users with a history of angry comments. A mere 0.1% of all Reddits generate 38% of attacks on others, and 1% accounts for 74%.