Depending on the gorilla glass type each version has its own toughness rating, only things that are above that rating can scratch the glass.
The extra layer would not prevent your screen from cracking is what I'm saying if you're still worried about scratches then throw one of the plastic like ones on and you'll be good. Just didn't want people to think a protector is gonna save a screen from cracking.
No one's saying a screen protector will make the device screen shatterproof; protectors make the screens less susceptible to breakage as they absorb impact energy instead of the screen, so in most cases the screen will survive. Going without a screen protector you’re going to get a limited number of oopsies before the screen suffers breakage of some type; a protector will extend that significantly.