its not. If I have it on for an example and you don't, the same player we are looking at could blend into the game more based on the coating they select. You can then say, well, ill have an outline. Ok, well then the outline should only occur when you're looking directly at the player. Anything more gives you more of an edge purely cause of how outlines works (UI overlays that require them to be brighter). Thus the game telling you "hey, bad guy right here" instead of you recognizing the player yourself.
Again, its all or nothing. Either do rvb or dont. It can vary on mode, but toggle is not a viable option.