I've noticed a difference between downvoting and non-downvoting discussions systems. In downvoting discussions, the top post will represent the consensus of the people engaged in the discussion. Note that this isn't "the truth" or "the consensus of the community" but of the people engaged on the subject. For example, if you see an otherwise-liberal community discussing gun-rights, the gun owners within that community…
But with downvotes, we ensure that only popular opinions get visibility, defeating the entire purpose of sharing ideas within a community.
The hope is both to increase friction and to allow each person to decide which downvote reasons they want to respect. It also forces people to foreground why they are downvoting and gets rid of "why the downvotes" and changes it into "why is this unproductive?"