Each post has a unique ID, and you can insert links to other posts in the text of your post. Then each post is given a set of back-links showing all posts that quote it. In this way, posts form a hyperlinked network that you can traverse relatively easily, while also being displayed in chronological order.
I've found this quite effective for long-form discussion. My only complaint would be that structure is needlessly limited. It would be better if posts simply formed a connected graph of content which you could ask the website to present in arbitrary ways.
This project reminds me a lot of Xanadu in its layout. I don't really think this complex of an interface is necessary. In fact, it might get in the way of productive discussion. I find that the constraints on other mediums (character limits, reply depth, etc.) often aid clarity. The transmission of information between people is fundamentally linear, and so you are pretty much always just going to be composing short essays and exchanging them as the basis of any real discussion. Complicated features seem like they would obstruct this.