Considering a pristine 6S is only worth $100 U.S. tops, I'd think spending $40-$50 for a battery that can be easily had for $10-$25 from 3rd parties it's not worth it to them.. They'll only supply parts for phones and products a few years old. 3rd parties have done a nice job offering parts for phones that aren't even supported anymore so they'll offer parts at prices that make repairs worth it