I’d also want to have an option to switch the marks’ visibility (and on default they should be off, to not distract from reading). With that, I wouldn’t even require author approval, it would be more like commenting, but line-specific.
So the reader particularly interested in some section could dive into the comments particularly about that section.
Also, as a further feature, you could color code different comment types, like:
yellow: fix suggestion
red: critique
blue: link to previous discussion / relevant resources
green: just a comment
FYI: I posted that suggestion on the EA forum feature suggestion thread, and also linked your comment
Add an option for drafts: “Anyone with a link can read”, but make it really anyone, not only forum users, as it is now.
(Recently I wanted to get feedback from some people who are not on the forum, and I had to copy draft to google doc, and later copy it back, and fix all the footnotes :/ )
Next step (but probably harder), would be to let anyone comment. If they aren’t logged into forum, these comments are anonymous.
Also collaborative editing in markdown mode would be useful.