yeah that too.Gosh I wouldn't take it on myself to try to tell the difference when it's somebody else doing it. I certainly wouldn't try to enforce a rule that policed that.
If I don't like how other people like to roleplay, I find new people to play with. I don't try to use rules to force them to roleplay my way.
If after you talk to someone that is doing things your group doesn't like, then that group is not a good fit for the player.