Another reason for requiring feedback for downvoting is so others know why it was downvoted. There have been many times where I’ve seen a dead comment on a topic I’m not familiar. I know the general user disagrees with that statement but I have no idea what’s “wrong” with it. Conceivably it’s because it’s obviously wrong to anyone in that domain so nobody bothers commenting or it’s a contentious issue in that domain and people who agree or could provide further insight don’t think it’s worth the negativity to bother commenting.

Either way I have no clue. I read a comment recently about setting up a graphics pipeline that seemed reasonable enough but was downvoted to hell. I would have liked to know why.