> The popularity of the service makes human moderation impossible, creating a need for inevitably-flawed robots

That's true, but we might be able to improve things with a bit more human moderation.

For instance facebook is insanely profitable. They could probably increase their staffing for moderation by a pretty decent multiple and still be very profitable.

So the current state of moderation is not strictly a matter of need, it's also a matter of greed in terms of Facebook wanting to automate away jobs they could pay people to do. And given the state of online discourse, it's a decision we're all paying for.