Then you have collusion, and this is what we want. This is a very typical control in regulated environments. It makes the action more difficult to execute, and it tends to carry an additional penalty as a separate offense.

This is bigger than trolling. We know people inspect the social network activities of others. This kind of abusive can result in all sorts of bad things. What if and admin didn't like you, edited your history, and then suddenly you lost your job for some fabrication of, e.g., a racist comment?