I am one who has only recently started to lighten my load. Not quite at the UL level yet, but still a whole lot lighter than I used to be. Right now, I have got my base weight in the 11 lb. area. Not bad. As I near age 64, carrying a 55 pound pack for 4 miles with 3000 vertical elevation gain ain't gonna happen again. With a 15 lb. pack, I can still do it and perhaps live to tell the tale.
But, I should like to weigh in on the BC stuff. I see similarities between BC and the SHTF crowd. (SHTF = when the brown matter hits the metal whirling blades...) The latter group often refers to "BOB" (bug-out bag) and some other acronyms. They include not only some of the older survivalist-militaria types, but also some thoughtful folks who just want to be prepared in case of natural disaster and other events. Some of those who frequent survivalist forums are worried about zombie attacks, or whatever in heck that is. As I understand it, they believe that there is a chance of economic/social breakdown which leads to "WROL", or "without the rule of law" events. This could include people trying to hurt you and rob you to get food and supplies for themselves. In my eyes, this latter group reminds me of the older survivalist types back in the 1970s and 1980s.
For me, I like the general notion of being prepared. I have a BOB which I put in my truck. It is a Maxpedition Versipack bag that has quite a few things in it. Pistol, ammo, flashlights, batteries, firestarting, emergency blanket, emergency poncho, paracord (and that is another thing --- to be really part of the WROL rowd, ya gotta have paracord!), water, compass, SOG Revolver knife, maps, compactor bag, vaseline soaked cotton balls, firesteel, altoids emergency tin, and other goodies. My wife and I have just gotten started volunteering for moutain search and rescue in my area. Hence, many of the things in my truck BOB are going to do pretty well in my new volunteer activity. I got to talking with the local S&R leader about my new effort to learn about UL approaches. He was very interested and we plan to get together and go over that some more. I now have my UL pack (in this case a ULA Conduit) already packed up and ready to go on a moment's notice whenever I am called to be a ground beater.
FYI, I also see that the BC/SHTF crowd has quite a bit to learn from the UL community. I will go out on a limb and say that, while we can learn from them, they have more they can learn from us. The reason I say this is that in a true SHTF situation, just hiking a few miles to your outdoor BC practice area probably is not going to happen. The hiking might be more like 15 to 20 miles a day. A lighter approach is for sure going to be better.
And to address the original question: I believe that the UL folks get out more than the BC crowd.
Blessings to all.