After reading "How to Have Impossible Conversations" (which was recommended by someone on HN a few weeks back), I've come to understand that the toxicity of social media has more to do with the lack of social cues, rapport building, and consequences than the details of the platform.
Also, "staring" conversations rather than "liking" comments still results in the same "sort by controversial" phenomenon: https://slatestarcodex.com/2018/10/30/sort-by-controversial/
Since ancient times, two philosophers would often have a debate by exchanging letters. The goal was not publicity, though many of such correspondences eventually became public. The goal, as I see it, was simply searching for truth. I wonder if it's possible to build a platform for something similar today. Even if it never becomes as popular as social media, I hope it could at least create a clear distinction between entertainment and actual conversation.