However, people wanting feedback beyond mere downvotes is legitimate and downvoting without comment is the actual wrong here IMO.

IMO the best scheme here is that you _must_ provide a reason to downvote. People who vote for your reason [ie they agree with you about downvoting the parent] should be the actual downvotes.

This way instead of apparently arbitrary downvotes one gets a list of reasons with scores (HNs score hiding aside, though they'd still be ordered) indicating their relative worth as reasons for downvoting.

That is actionable. Under K2I that would allow everyone to tailor their contents to the audience if they wished, or at least understand the audience's approbation.

tl;dr I downvoted you ;o) ... except I didn't because your comment has value even if I disagree !