alt Hacker NewsNewspaper "Letters to the Editor" manage to do this. Users "submit" things to the newspaper, the editor curates and decides what to keep and what not to, and then the newspaper publishes the user generated content. Just like social media: Users submit things to the site, TheAlgorithm curates and decides what to keep and what not to, and then the site publishes the user generated content.
If web sites and social media can't "scale" to do this, then maybe they should scale down. "Making sites liable for all user-posted content" would not kill social media, but would definitely scope it down to what can be effectively curated.
I don't think there are enough dangs to effectively curate much of the internet, and scaling it back by how much would be the result? 95%? That is before settling on definitions of effectively curate I suppose.