I too am a scouter with decades of traditional backpacking experience. After a couple back surgeries, I found this site while looking for ways to lighten my load so I could survive Philmont and keep up with my boys.
I agree with many of your points... Some of the techniques on these forums do not work well for large groups (like alcohol stoves), inexperienced scouts (lots of down bags/clothing), or within the confines of BSA/Philmont rules (tarps). On the other hand, the overall goal of this forum is to lighten your load as much as you can while still being safe about it. When I arrived at this forum, I thought many of these ideas were extreme, but after letting them sink in, then actually trying some of them, I'm starting to see that maybe they're not as extreme as I had originally thought.
Regarding some of your assertions about Mr. Prosers gear... Would one set of briefs work if they were washed and dried every day or every other day? How about socks? If you have two pair PLUS a sleeping pair, could you get by? If it came right down to it, could he wear the sleeping gear as an extra layer if it got unseasonably cold or his primary clothes got damaged? If he's careful about keeping his rain gear handy, how likely is it that he'll get completely soaked before getting it on? If it's wool, won't it keep him reasonably warm anyway? And so what if an item did get destroyed? Should he carry an extra of everything just in case? At Philmont are you ever more than a day from a staffed camp?
For Mr. Prosser, his setup works because he knows his gear, knows it's limits, knows how to care for it, and is careful with it. Even if you're not willing to go to these extremes (and I'm not), many of Mr. Prossers (and others) suggestions can be incorporated into a Philmont trek (or any Scout trek) to a lesser extent.
Case in point: I went backpacking last weekend with a few boys last weekend... A 1-night 10-mile trek with no rain in sight and temps ranging from 98 in the afternoon to 72 at night. One boy brought two pairs of shorts AND two pairs of jeans. That boy NEEDS some of the advice of this forum lest he hurt himself!
Someone on this forum wrote that you pack your insecurities. I couldn't agree more. I used to pack a lot of stuff in order to "be prepared", but this forum has reminded me what scouting taught me int eh first place... That the best tools in my gear kit are knowledge, courage, and a can-do attitude. I'll probably never get to Mr. Prossers level of sacrifice (I do like clean drawers, fresh socks, and overly thick sleeping bags), but a lot of these ideas will go with me on every scouting trek I take.