Go look and tell me that's not one of the best curated communities on the internet, despite specifically covering incredibly controversial topics. HN is good but doesn't even come close.
The rules they enforce on normal posts are so strict that they have to create daily "mega" threads with less stringend rules just to keep the sub on life support. A+ moderation, clearly a healthy and well managed community.
The split works very well, the megathreads mostly stick to tracking rapidly developing situations in which separate threads would just be spammy and unnecessarily fragment the conversation