That sounds like a free market. A government provides a minimal container and you’re free to create your own sub-pocket with your own rules inside of that structure. If you don’t like the rules of sub-pocket A (ex. Twitter), you can go create sub-pocket B (Truth Social). And they have no centralized style of rule enforcement because they are their own unique private enterprises.
Maybe the problem isn’t Twitter. Maybe the problem is expecting Twitter to act like an unbiased government when they’re not. They’re a for-profit sub-pocket with their own subculture. Just like Reddit, YT, FB, TikTok, etc. They’re all competing for eyeballs and ad dollars while independently enforcing their own rules.
The different 'subpockets' will be competing for expansion as organisms in an evolutionary environment, but describing it was a market would be using the wrong model. The trend of simplifying every free organizations as markets is harmful to rational analysis, and I'd say it comes from over-reliance on a set of values that see it as the only valid tool for solving every problem - i.e. an irrational prejudice. We should do better in our analysis of the evolving world, since society is going through never-seen changes and applying old recipes will limit our understanding.
I'd say the first and only rule is that there aren't any rules that everyone must follow. There will be subpockets with different subcultures, with each one building and enforcing their own set of rules, but no single centralized style of enforcement.
No commercial network with a company backing it could ever offer a space like that, because they are liable to monitor and moderate the worst content that goes through their property, thus creating a single centralized culture based on the company's values.