I've called out hate speech on 4chan and 8chan many times before. I've gotten called an "SJW cuck" a lot, and others doubled-down in posting shit gleefully when they saw their shit "triggered the libs". That was the fun part to them. To someone like me who isn't there just to challenge people, it's exasperating. I gave up and they didn't.
I think certain site structures encourage different kinds of discussion. Imagine the most extreme possibility: a site that automatically hides posts that the majority would agree with after reading, and gives points to and highlights bombastic posts. You're not going to get good discussion out of this, no matter how much you try to convince people that it would be good for society if they visited this site and tried to challenge people there.
I think imageboards like 4chan and 8chan accidentally approximate this. They bump threads to the top on every reply, so threads that trigger flame wars are incentivized. The lack of names means no one will call you out if you flip-flop opinions, so you're free to flip-flop to whatever opinion will trigger the most people, which users will do in order to make successful threads.
After a few cycles of this, normal people ("normies") either leave or adapt themselves to fit in, so the remaining users have to amp up their ridiculousness to make threads that are bombastic to the new crowd. Users get used to having to make their opinions more extreme to get noticed. I think this then causes them to flock to threads that they can tell are bombastic to normies as a way to self-reaffirm their own tendency toward making bombastic threads. If you ever try to argue for the normie opinion on a subject, it "outs" yourself as someone who isn't a true user, as someone who isn't purposefully ratcheting their opinions up into offensiveness as the site encourages.
Years ago, I helped run a once-popular imageboard dedicated to a fandom, and its level of dysfunction was legendary. A big part of that probably came from the userbase's overlap with 4chan, but the way problems regularly cropped up in common interactions even in topics and groups of users with little 4chan overlap made me skeptical of the structure itself. It helped a lot being able to see which anonymous users made which posts and see how common it was for people to sock-puppet or radically re-work their opinions in their next thread.