I've had my S8+ for 5 months and it's scratched to hell. Always in a pocket by itself, never put face down. My wife has my almost 2 year old S7 Edge, in her purse, back pocket, face down, pretty much every way possible and still not one scratch. I know I'm not the only one with the problem. I think we all need to bombard Samsung and make them stand behind the GG5 and offer in warranty screen replacements. What good is a thousand dollar infinity screen if I go to show someone and it looks like **bleep**?
Even with Gorilla Glass 5, I would still advise a nice screen protector on your phone (and a case). I've been using Skinomi TechSkin on my S7 and it's a great screen protector. It's a worthy $10 investment.