I'm just not used to Apple products having bad battery lifespans. Coming from the beginning with my 3GS and first 4, now my 6S and the fact my mom has a 6S that shows 65% battery health yet still makes it through a day plus on charge. It's just not worth the hassle IMO. The only reason her phone is at that low a level is because she leaves it connected to a third party charger for days and forgets it. Still manages decent run time regardless.
Then my PowerBook G4 Titanium still having a usable battery but compare that to some 2001 era Compaq laptop which needs the battery removed to even power on with the AC adapter connected.