Its the other way around. Apple determined it was detrimental to their bottom line to repair and resell devices older than Iphone X. Devices with cracked screens, requiring battery/ charging port/ case/ button replacement, of fully working traded in https://www.apple.com/shop/trade-in ones. What do you think happens to perfectly working iphone 8 plus worth ~$300 after its been traded in? Its not being resold https://www.apple.com/shop/refurbished/iphone , it goes into a blender https://www.youtube.com/watch?v=AYshVbcEmUc