Though I would also argue that one of the biggest negatives about Reddit is that you can't come back to a thread later that day or another day, if you want to get your reply head then you need to respond immediately and attain a lot of upvotes. With a forum you could respond whenever you wanted and get a discussion going. And similarly forums would allow you to avoid the echochamber effect by avoiding upvotes/downvotes as everything was chronologically ordered, so it was a much more civil affair.
But I agree that the chain-of-quotes is a positive about Reddit, which I think might be possible to implement/merge into a new forum design.