That would make it an explicit cheat. Right now, not publishing negative results, tweaking the procedure description a little and things like that lie somewhere in a gray zone and can be socially acceptable in some lab to some extent. However, if this would be explicitly defined, breaking this would be an explicit straightforward lie, which would make it harder to make socially acceptable in some limited circles, people would have to go to greater length to hide it and this kind of thing would not happen that often.