Define "clear and explicit rules". Does the constitution of say United States qualify as examples of clear and explicit rules? If yes, then even after roughly a quarter millennium, there are still hundreds of thousands of cases filed each year.
If an online platform creates an unclear or vague rule and use that rule to remove a user, then that user could pursue legal actions. If a court agrees that the rule (or rules) used to remove the user from the platform is unclear or too vague from the perspective of a reasonable person then the platform would need to pay out for their mistake.
Therefore it would be in their interest to ensure they have clear and explicit rules.
I don't think this is hard and we shouldn't pretend it is. It's just regulators in the West rather force Apple adopt USB-C and destroy E2E than than protect us from arbitrary corporate censorship.