FormerlyHemlock
Hero
Yeah, (most) rules are less about what you can say, more about what the universe says back to you.There are rules that do that, but that's not why RPGs have rules. I really, really doubt that outside a small handful of times(at best), designers have sat down and said to themselves, "Let's figure out who is allowed to say what in respect of what happens next in the shared fiction and then make rules to match that."
Rules are there to provide structure to the game and avoid Calvinball, allowing the group to have more enjoyment out of the game. What kind of enjoyment you seek will determine which RPGs appeal to you the most.
There are some exceptions, e.g. taking turns in Monopoly or in 5E round-robin initiative are restrictions on when you're allowed to talk. (I hate round robin initiative because it's an unnecessary and unpleasant restriction--it shouldn't matter when you talk, it should only matter when the universe talks back to you.)