Good question.
I cannot find the reason either...
the only reason is that airbus has not updated the FCTM because what you are talking about is stated as a master caution, but looking in the Fcom 1 it says NIL for any caution...So this is also wrong...
Before I belive they also had ELEV R+L fault, but now they have removed it, at least here...
I am not sure though...