Facebook could have chosen to be a completely neutral platform. They could have followed the ISP model, making Facebook another platform like email, RSS, or htt

Facebook could have chosen to be a completely neutral platform. They could have followed the ISP model, making Facebook another platform like email, RSS, or http. They just had to not make editorial decisions - leave the feed sorted by recency, and only remove illegal material. This is what safe harbor provisions assumed a company would do, allowing platforms who simply pass information between parties to avoid liability for that information. But they wanted to be valued higher, so they explicitly chose to instead step into the editor's role and became responsible for the content on the platform.