Frankly I think it's because it doesn't really make sense in terms of general lore. There really shouldn't be a Horseman named Fury as Wrath and Fury are effectively the same thing, hence the reason while the Black horseman is typically Famine.
He gets weaker when he doesn’t have anger to feed off her. When there’s more anger he becomes more powerful and grows in size. When there is no anger he shrinks in size and grows weaker.
