Read "Amusing Ourselves to Death" by Neil Postman.
You will realize that Social Media is designed in such a way intentionally to draw toxicity from society.
No technology is neutral. Technology gives and technology takes away. Medium is the message. Communication evolved because of the medium. For every evolution, it gives something and it takes away something. From oral communication to the printing press to telegraph to TV to the internet to social media. Every evolution gives birth to something and destroys something.
For example, TV makes everyone reachable (what it gives), but makes everything into entertainment (what it takes), even important topic such as politics, religion, war, poverty, pestilence, etc science becomes pure entertainment, juxtaposed between endless drama, reality show, and ads, coupled with background music and personas that manipulate the minds. The more "entertainer" you are, the better, regardless whether you are a dumb scientist or a dumb lawmaker that will affect many people's lives using your policy.
Social media such as twitter, for example, everyone now has a voice (what it gives), but with its char limit (what it takes) doesn't give critical thinking and rational debate a highlight, therefore it spirals down into madness. The more outrageous you are, the better, because it will go viral and people will react in such a predictable way.
A good example of a person who knows exactly how TV audience and social media audience will behave in a predictable way, and took advantage of that, is President Trump.
You want to design a medium/platform in such a way so that the pros outweigh the cons. But I think the hard part is knowing how will people use the platform. Those social media giants started out with good intentions, and only later and later down the road, and here we are right now, that we discover its true effects.