Battery sizes in flashlight design

[Niagara]

Coming from a wealth of knowledge in product design and battery technology in my business in the vape world, as I delve back into this forum I was active in may years before seeing and todays variety of flashlight designs sold I am surprised by the over abundance of small low amp draw/capacity batteries being used like 10440 and 16500 batteries in some flashlights. I am also surprised not to see more 21700 batteries being used for their relative safety high amp ratings and capacity. Personally I would rather have for EDC a short tube with more amp capacity., then a longer narrow tube. Plus their is way better selection/availabilty of 18650 and 18350 batteries from reilable sources.