An idea along those lines: every item (submission/comment) should have a separate set of children that are 'meta/correction/derailing'. (That is, there's 'reply' and 'reply-meta'.)
Users would have to choose (or earn?) 'showmeta'. (So, no clutter for those who don't want to see that level. But perhaps even people without 'showmeta' see the meta subthreads on their own authored items, and a count of unseen metas-in-reply-to-them.)
Minor editorial nits like typos/headline-improvements/URL-improvements ought to be raised in 'meta' replies... and normal replies can be moved to 'meta' if appropriate, even beyond the normal edit-grace-period - especially if their point become obsolete by parent/admin editorial action.
Perhaps meta-items even have a one-tick way for the parent/admin to acknowledge they've been seen, mark as agreed, or mark as addressed.
All in the spririt of subtle-behind-the-scenes work to keep the "foreground" that most see on-point and high-quality.
(Better to continue this conversation at hn@ycombinator.com.)