I don't recall ever seeing these people actually successfully reassembling anything they have torn down. They talk about repairability, but never seem to actually show the outcome of a repair.
Plenty of us do care, though, and I tend to hand down or give away my retired phones ones of trading them, and I prefer to hand them down with a fresh battery.
In general, people are keeping their phones longer, so battery replaceability matters. 3-4 years is becoming the norm.
That's your choice however I am not in the habit of handing off old Apple hardware for someone else to have issues, and especially the longer hardware is kept the further it devalues. If AppleCare won't cover it and the cost to officially repair the device to its original state is too high, I simply accept a trade-in value and then pay the difference for another one, or keep a store credit on my account for use later. I am not a charity and do not give things away and "handing down" a phone means no financial return (no matter the amount). I have had to work to purchase what I have and no free rides for anyone, including family or extended family. People value things more when they work for it, not when its given to them.
I would never and will never repair my own devices and do not expect the manufacturer to bow to the whims of the minority. The tools / time cost / part cost / shipping and free labour to do it myself (which adds to the original purchase price), in the knowing that the device will never be the same as original (especially water sealing), is literally and metaphorically not "worth" my time, plus AppleCare cannot be applied due to the devices age, plus I will get no further performance from it either. Just from a $$$$ perspective when it's all added up, it makes no financial sense.