10% damage reduce to fat guys. Can somebody explain me idea behind that??

i am terrible too, i'll have a shotgun as an example if i have a peacekeeper and i make a shot on a octane for example it will do some damage but if i do that same shot on caustic then it will do a lot of damage, honestly i think 10% is pretty fair overall especially since both caustic and gib had by far the lowest winrates and pretty sure the lowest pickrates