The key precedent that needs to be established is that social media users are part of a business even if most of them just think they’re there for the party. Because even for them, the party’s only free because someone in corporate bizdev paid for their ticket in order to market something to them.
If the users of social media are parts of businesses and the social media companies are themselves businesses, then the relationship of user to platform is not that of a guest to a host, but of one business doing business with another business. That’s how law and society should view the situation because that’s what the situation actually is. Social media is B2B.
When you’re in a B2B situation, what you cannot do is be dishonest about what the rules are. If the real rules are house-party rules—which, to repeat, they actually are and must be—then you have to say so, out loud, and in writing.