I don't think you can solve it because it's not the platform, it's the userbase. Although voting systems to highly encourage downvoting/upvoting based on whethe

I don't think you can solve it because it's not the platform, it's the userbase. Although voting systems to highly encourage downvoting/upvoting based on whether you agree or not. An idea I've had is to rank all content separately for each user, by predicting what content they will upvote or downvote. At first it sounds like this would exaggerate the echo chamber effect, but I think it would do the exact opposite. There's no reason to downvote or upvote things because you agree or disagree, downvotes only affect what you see in the future and no one else sees them. And instead of different ideologies being pushed away into different communities, they all exist in the same place, occasionally interacting with each other and mixing.