More specifically, this Advantage makes tackling robots extremely difficult with old-fashioned kinetic based firearms.
Here's an example: you're fighting a Mr. Gutsy with a "Chinese Assault Rifle" (basically, an AK-47 derivative copy). The gun deals 5d+1 pi damage (Average of 18.5 damage, rounded down to 18), and Mr. Gutsy's IT: Unliving divides pi damage by 3. Let's ignore the fact that the DR on this thing would be substantial (12 is a conservative number). Heck, let's ignore DR period. If you give a Mr. Gutsy HP 16, then that's an average of six shots before it needs to make it's first death check.
With DR 12, you're doing 2 damage per shot, which means sixteen shots before it needs to make it's first death check.
By the way, most conventional firearms are not as powerful as the CAR, so the problem only gets more prominent when you're using pistols and submachine guns. Even a .308 sniper rifle is not much better off (average of 8 damage).