For instance, would you carry an iPhone the size of a shoebox if the rest of the space was a battery? Would you even be willing to carry one of the 80s phones that had a satchel?
I have a large external battery that I carry at camp at times. Mostly it sits at my tent getting charged on solar, but I have carried it for an short time to charge my battery while doing something else. The youth at the camp don't carry a phone, but I often get asked to look something up for them so it is useful. Not to mention when there are no adult activities to keep me i entertained.