Why dont multiple sch shield stack?

[Nicobo]

As it this now. Whm are able to stack the heal over time from their medica 2 on the same target. what I mean is that they can both be applied at the same time. But why is every shielding ability from multiple scholar not in this case? Only the strongest shield at a certain moment is applied, removing the other one. I think it makes it increasingly difficult to have 2 sch. (From exp 2whm goes a lot smoother)

Simply, Pro and SS don't stack, it is system design consistency regardless op or not.
IMO they will just nerf it in advance if it could be stack. ^^;