Why is a platform responsible for the behavior of its users? If a person throws a knife and kills someone, we don't go after the knife maker. Yeah, I know: it

Why is a platform responsible for the behavior of its users? If a person throws a knife and kills someone, we don't go after the knife maker. Yeah, I know: it's hard to go after an individual. Guess what? It's hard for a platform to go after an individual too. I don't do any social media crap and think its a huge waste of time. But the government saying social media is responsible for people's shitty behavior doesn't really make sense to me.