I don't think you understand the issue. I'm very disappointed to see that this is the top comment. This wasn't an accident. These social media companies deliberately feed people the most upsetting and extreme material they can. They're intentionally radicalizing people to make money from engagement.
They're absolutely responsible for what they've done, and it isn't "by proxy", it's extremely direct and deliberate. It's long past time that courts held them liable. What they're doing is criminal.