My old sleeping bag was ultralight with a sewn-in stuff sack so I never used a compression bag, so it was kinda bulky for its weight. My old tent was sort-of ultralight then. The same model now is even lighter yet only "light" among other models. Not everyone has the latest and lightest. Could be lack of knowledge of what's available, inexperience to know one's needs, budget, using older equipment that still works, or just not caring about weight. Then If you're into hobbies while touring, like photography, (DSLR + lens) wildlife photography (+ long lens), dayhiking (+daypack and shoes), backpacking (+big pack)... it can get heavy fast.

When I pack for flying, everything on this bike fits in the rear panniers and the bag on top of the front rack. That includes the tripod, front panniers, a full size backpack, even 2 stoves. I use two panniers on short trips but prefer 4 on longer tours. Things are better organized and not so crammed. The bike handles better and there's more room for food. Not just more food but bulky, crushable food. I was going on a 5-day hike on my last trip so 2 days to get there, 5 days of hiking without resupply, plus a day to the next town. The only store was a cafeteria and c-store with limited hours and choice. The extra room was welcomed.
Slowly.