There is a 4th option - treat certain surfaces of social media companies, mainly the user specific pages (Donald Trump's twitter page, PewDiePie's YT channel etc) as a platform; treat other surfaces which are generated based on algorithms and not directly by individual users (FB feed, YT watch feed, reddit homepage etc) as a publisher. That way, social media companies won't be responsible for what their users upload. But they will be responsible for what they present to their users to optimize clicks / engagement / revenue etc.