If you host blobs for free, somebody is going to use you as their host. Even if you just hosted audio, I'm sure somebody will quickly come along with a steganography tool to hide their content on your site (and use your bandwidth). Similarly, if you make compute power available, people will use you to mine cryptocurrency. Even if all you host is text, somebody will come along to be abusive. When you put a computer on…
Yeah, there's an entire category of "idea guys" who don't get this. They repeatedly try to crack the code on a truly moderation-free or purely crowd-moderated platform, and it never, ever, ever works. It almost always boils down to a poor understanding of how humans work (usually some sort of "homo economicus") or how computers work (usually some sort of "AI magic wand").
My bet is some real-world tie, one which is time consuming and expensive to create. From there it should be possible to create moderation tools that keep the rest going.
An example of a real world tie would be a trust network that requires status with in-person communities and local businesses. And not just "accept the hot chick friend request," but an explicit "I'm staking my reputation by saying this person is real."
But once you let bots in, it's over.