Not necessarily. I personally want to be competitive in whatever division I'm in. But I absolutely do not believe that doing so will come down to a few hundred pounds of weight - or even kevlar sails.
That's the beauty of longer off-shore races - it's more about weather, routing, and long-term focus on the boat's performance than ripping out the head to save weight.
When boats in a race are separated by 100ths of a second at the finish, then I might become a believer in the typical BS and think about taking off that extra layer of insulation around the cooler.
Regardless, I'll let my crew know what's up.
By and large, you are right that the mistakes you make in routing, or even a sloppy tack or spinnaker raise or jibe, can cost more time than a few pounds of beer, a non-race bottom job, or a kevlar sail. But whether or not you optimize the boat, you are still going to make the same mistakes in routing, a sloppy tack or bad spinnaker raise or jibe.
Over the course of even a distance race, the kevlar sail might mean a few less sail changes or not having to reef or shake out a reef a time or two or three. The cleaned out lockers might mean a few seconds a mile. The smooth bottom might mean 8-10 seconds a mile and pointing higher or maintaining more speed through waves. Collectively over a long course these things add up to some pretty big numbers.
Its kind of like a funny thing that happened a few decades back. I always had a friend who would tell me how much faster my boat was than his, but he would also joke that if we switched boats I would probably still beat him home. We had both single-handed over to the Rhode River so I thought, why not see how that works out. He was basically right that I was able to beat him home but by a very small margin. My lead was basically the result of a tactical decision to sail to where I expected less current and the wind to fill in sooner which took me from way behind to slightly ahead.
On the other hand, and in the interest of fairness and humilty, coming back from the first Sailnet Rondezvous, one of our members with a Sabre 34 cleaned my clock. He did as great a job of putting his boat where there was breeze, as I did finding windless holes. Whenever I'd catch some breeze, I'd have more speed and I'd close the gap even pass him. But inevitably he cleaned my clock.
The temptation is to say, that these prove that a faster boat won't get you there any faster, but the reality is, in the first case, had I been in my boat, I would have beaten him by way more than I did, and vice versa in the second case, since both sailors would have sailed essentially the same course, been able to take better advantages of some of the smaller events along the way, and made essentially the same mistakes and good calls.