Part Pairing
I was able to make a 5th generation iPod better than any available at the time of release by upgrading it with solid state storage and a colossal battery (occupying the space where the thicker hard drive was). It can now play music continuously for around one week and has the capacity to back up that endurance. If I had to use an internet-facing portal to authorise those part swaps, I likely wouldn't be able to because they're third party and, even if it were supported, it would only be by Apple's good graces if the portal were still available after the 17 years since its first release.
It is very much in Apple's interests to shutter any mandated support the minute they are allowed to.