My point is that it's not "a penalty specific to summoners". A NIN gets less flat delay reduced from a haste spell than a 2 hander. A WHM gets less flat damage reduced from shell than a BLM. A SMN pet gets less flat damage reduced than a BST pet.

But they all get the same *percentage* reduction of whatever it would be without the thing in consideration.

It's just the way the math works, and asking it to be changed for SMN is asking for an exception to the way multipliers work for every other thing in the game.