they havnt actually played GP to see how he works against other champion's.
GP is not a crit to win.
Have you tried to CC him twice?
first example that pops into my mind. Taric.
Stun > cleanse >stun > cleanse on CD because it's only level 1 and has a 17 second cooldown.
And that's if one champion has a cc.
If the GP player payed enough IP to rune a full page of Apen and crit dmg runes, then yes rush a brawlers and crit chance, and melt face.
He will still lack mana, and hp.
If GP is harrassing you with Q, BUY POTIONS.
Running flat crit for early game dominance is much better then CrD or ArP imo, nothing like getting a 275+ crit at level 1 off of parley which then slows the enemy, if you're running exhaust the champ is gone. It's not hard at all to zone people out of lanes with GP with his amazing farming, harassing, and ganking potential.
Also if you don't rush crit bracer you can easily afford health and mana pots to cover you until you decide to port back to collect more items. IMO early game GP only needs a bit of mana regen to dominate his lane and if he's mid there are very few champs who can zone him out if any at all.