I think the thought is that a heavier pack means you are more macho than the next guy. A heavy pack doesn't feel all that heavy in your living room. After all, you do have a chair, 3 changes of clothes, pots, pans, lanterns, bivouac equip., storm rated tents, 1.5 lb. footprints, C Cell Maglites, towels, leather (not ankle turner) boots, 4 pairs of heavy wool socks, and many more items that make you will feel just like you are at home.
I was amazed at the old school approach at Philmont. However, if you do read the Philmont handbook it stresses lightening one's pack weight. They suggest a total of 35 lbs. The only problem is, people think that means 35 lbs. BEFORE you get there and add troop gear, food and water. That's why in the UL crowd BASE weight is stressed so religiously. Keep the base weight low and the overall weight will not be too hard; even at Philmont. I told the boys and the leaders to pack like they were just going on a 4 day hike. One of our leaders was 63 years old. He could not thank me enough for having spent the time with everyone to teach them the techniques we have all learned here on this website. He had given up on backpacking. It was a big payoff.
On our final day we kept picking off crew after crew. Our loads were at their lightest and we were just cruising. Other crews would just pull to the side of a set of switchbacks when they saw us coming with what must have seemed to them a bunch of scouts wearing day packs. It was fun. One troop tried to overtake us from behind on the way down from Tooth of Time but finally gave up. Lightweight at Philmont is the only way to go! Wimps rule!!!