How so? Wikipedia is a bad example as it is probably one of the most heavily moderated sites on the web. Social media is still 100% possible, it'll just be impossible to scale overnight as you'll have to scale moderation efforts with your username.
Wikipedia is heavily moderated, but primarily by volunteers. Do you think that would be sufficient if the Wikimedia Foundation was liable for anything bad that users might post? That’s putting a lot of trust in your community, and the consequences of volunteer moderators slipping up or missing something are pretty big.
