Anonymity, ephemerality and equality. I can explore multiple aspects of a topic by formulating different responses in different posts (e.g. I can answer as myself in one post and be the "advocatus diaboli" in another) without others tying the text to me personally, posts are not put in a visible hierarchy, and what's been written is gone forever in a while (ever discussion has to be restarted regularly).
This means every discussion here is much more pure, diversed and current than on other platforms.