Happy Feet

Weight is important in a theoretical sense but it does not take into consideration two important points:

1. The intended purpose of the tour.
I just completed a 780km trip in less than 4 days with very minimal gear. No cooking gear, one set of clothes (with weather layers), no book or entertainment other than an ipod. It was successful even though it was spartan because the main goal was to do a quick tour of that distance. My enjoyment was in riding farther faster. The weight was important to the goal.
A couple of years ago I did a week long Gulf Island tour with my son and brother that covered only a fraction of that distance and had a full kitchen kit, cards, books and extra gear of all sorts. It also was a success despite the additional weight because the main goal was to enjoy the day to day experiences like meals and games with my family, not how many km's I could crank out.

2. Disposable income.
Each person has only so much disposable income to dedicate to the act of touring and weight savings is partly a function of what you can leave behind and the reality of the cost of the weight you must bring. While some basic weight saving choices don't cost too much there is a point where additional savings depend on paying more for the product. How far down that rabbit hole one goes depends on how deep your pockets are and how important that weight savings is.
Added to that idea is the law of diminishing returns wherein increased cash outlay yields some, but minor, weight savings. Chasing grams can be an addictive challenge but at some point it becomes an activity in itself divorced from the enjoyment of a bicycle tour. The enjoyment primarily comes from creating an increasing light rig instead of enjoying a tour with it. At that point, usually, one can garner as much enjoyment with x amount of weight as another with y. I don't think that's 70lb's vs 10lb's but maybe 15lb's vs 10lb's might be closer, depending on the main goal of the ride.

I've been looking at this years Trans Am race and the bikes being ridden. Many of the scratches have very nice lightweight bikes but, for one reason or another, that did not help them. Besides weight there are many other things that go into a successful tour. No offense intended to any racers - simply meant as an observation.