Dang, don't know how you breathe at that elevation!!! At sea level you can probably hold your breath for an hour. Anyhow, indeed, even when I'm hiking on just the State Land, I always carry the same pack and gear I would up North in the mountains. Sometimes I'll carry the same, even a rifle, taking the dawg on the two or four mile "loop" of my rural neighborhood. Yes, one can walk down the road here with a rifle and no one cares. I have seen "others" doing the same. There are "others" "out there"!! So it makes sense to carry one's gear, or at least a pack of the same weight on a serious hike, when doing a more casual hike.
I also have a very heavy "get home" pack, but I pack it so that I can off load much of the gear, should I need lighter weight, instead of that gear. Make sense? You never know what the situation will be, but it's good to be initially prepared for "everything" or anything. But after assessing the "situation", there will be things one can dump to lighten the load. So maybe that friend wasn't so dumb if he was willing to dump gear, that was not going to be needed, according to what was going on. ? If it turns out you only have ten miles to get home, but you're packing four MRE's, (I have four in my "get Home" bag) then just toss a couple, or give them to someone less prepared. I have other stuff "just in case", but I'm not committed to taking it with me no matter what. But good to have initially, in case what matters. Or something like that.