However, I'm not sure I agree with your assertion that civil dispute resolution mechanisms for defamation have to constitute a restriction on speech. People can still say whatever they want, whenever they want, to whoever they want. They can merely be called out if they are lying.
Without a government to enforce that you stop lying, through fines or even prison time, how do you stop someone more socially powerful than you? You can call someone out and be right, but if they're more charismatic, more popular, or better at marketing their point than you, you still suffer.
> Without a government to enforce that you stop lying, through fines or even prison time
Is libel not a civil offence? I.e. the court case is person vs person not state vs person. You confront the person lying in court and if on the balance of probabilities they can't demonstrate what they said to be true then they pay you compensation (plus costs). No one goes to jail, no fines are levied. The government's role is to provide a judge (and potential jury) and court room.
Well this would be a debt from the person who has defamed you to you (and potentially a debt to the state for their share of the court costs).
I'm not massively familiar with what happens when someone doesn't pay a debt. As I understand it though. A civil case is heard, bailiff's arrive at the debtors property and their possessions are re-posed until the debt is cleared. These remain civil proceedings not criminal.
However, I'm not sure I agree with your assertion that civil dispute resolution mechanisms for defamation have to constitute a restriction on speech. People can still say whatever they want, whenever they want, to whoever they want. They can merely be called out if they are lying.