Universal truths are sometimes assumed. What are universal truths changes. Sometimes, so much "truths' later turn out to be folly.
There's a huge disconnect here in the posts. Saving weight backpacking does not have to cost ANY MONEY or PURCHASING ANYTHING despite our tendencies to incorrectly assume otherwise patterned by a culture that tells us money and shopping are always the solutions. Here, yet again in abundant evidence, we are habituated to saving hauled backpacking weight thinking only in terms of gear weight.
What does saving a ounce of weight cost? Knowledge and trail savvy wisdom! Saving an ounce of wt is as simple as not carrying a bag of M&M's, that unnecessary hauling of more H20 than needed - 2-3 capfuls, ending a hike with left over food or fuel, or taking an extra uneaten granola bar.
There is entirely too much focus on money and shopping for gear to lower wt hauled when the largest single category of any one item most carry on multi day hikes are consumables. Not sexy, exciting, or entertaining enough though compared to the incessant never ending chatter about saving the tiniest amount - one ounce - on gear wt though, hey?