> The oldschool forum format requires a lot more scrolling and superfluous content that is unrelated to the discussion

On the other hand, the flatness and default chronology of those scrolls provide a reliable WYSIWYG experience the Reddit trees lack.

E.g., forum noob reads scrolls and sees X% of $bad. Forum noob posts new scroll prepared to get tolerable level of $bad (or hopefully less). Forum noob2 then comes and considers X% of $bad intolerable. Forum noob2 gets deterred from posting a scroll.

Tree noob reads trees where the visible branches do not contain $bad. Tree noob gets unexpected level of $bad in the first Y minutes. After Z minutes, 100% of $bad has been folded away into hidden branches.

After Z minutes, Tree noob2 reads the tree with no visible branches containing $bad. Tree noob2 decides it is safe to post a tree...

Same problem for branches shuffling over time. You can read the Bitcoin pizza guy's scroll today in the same order everyone else did. But even on HN, how do I play back the branches shuffling up and down for the responses to the initial post about Dropbox?