The point of perfects isn’t to render you immune to extras or weak opponents. Even in 2E just having a high enough DV will do that.
The point of perfects was to render you impossible to destroy to things significantly outside your weight class. It was to justify the Exalted host slaying the Primordials and not being Wish spelled out of existence. Perfects exist so that you can survive an attack from beings whose size begins at “mountain range” and moves up from there.
Just like Ghost Eating Technique is a thing that exists partially in setting as “the Exalted can kill anything, even things that can not be killed.”