Could we think about repurposing the down-vote function to serve a different role? Similar to the report function, which signals a need for moderator review, the down-vote could be used in the same way to flag content that might require a second look. This could assist in handling extreme or illegal content without suppressing diverse opinions or content simply because it doesn't receive wide agreement.
What if we displayed only the "+1" upvotes on the website without showing any down-vote counts? This would maintain a positive atmosphere and could encourage more open dialogue. Essentially, a down-vote would transition from meaning "I disagree" to "this might need reviewing".
Importantly, if content isn't extreme or illegal but still gathers a significant amount of down-votes, it could be an indicator for the moderator to assess if further action is necessary. This shifts the down-vote function from being a tool for disagreement to a measure for maintaining the quality of discourse.
Reddit did try this, they use downvotes as a way to prevent showing poorly written or short content, but they didn't properly explain it and so I feel that it probably wouldn't be able to be explained.