Gear doesn't make you play better but makes you perform better than a similarly skilled player with lower gear, and makes you outperform better players than you given enough gear difference. It also gives you a way to work around your own skill failures. Failing to dodge a titan HM bomb on ilv50 means you're dead. Failing to dodge a titan HM bomb on ilv90 is a minor incovenience.

Also, first thing I can see about a random players IS his gear. If I have to choose between two random players of the same class for my party and I don't know anything else about them, I will choose the better geared player every time.
And let's not forget some in-game full gear checks you cannot overcome with skill alone unless you're the top 1% skilled player.