I think that fitting can play a huge difference in how you can play. I think many go for a driver fitting and are disappointed because it "only goes 6 yards longer. I think the real benefit is iron fitting and narrowing dispersion and regulating spin. If a fairway is 25 yards wide and I am 8 yards to the right side of the fairway compared to the middle it probably won't make much of a difference. But if i am 8 yards right of the green compared to the middle it will. Yes, swing can play a large part in that, but optimizing the club for your current swing eliminates one variable. Most of the services will adjust clubs if your swing improves and the lie needs to be changed 1/2 of a degree. Not to mention the mental confidence a player can have knowing it was the swing and not the club.
Also in the long run it may be less expensive but getting 1 700.00 driver than trying 5 380.00 drivers.
I think people should get fit for a putter also.