If you put the icloud-lockout stuff early enough in the boot chain (which I believe is the case on apple silicon macs already?), that seems like a solvable problem too. I can understand why apple hasn't put the engineering effort into making something like this happen, but I don't think it's because they can't make it happen.

And it is not stopping people from steal IPhones as they can resell parts as usual.

The stolen parts have serials on them that get blacklisted. iOS isn't going to run with a camera that's been marked as stolen.

And the consequence for this is that you can't replace your own camera - or home button. Instead of a thief stealing your phone, Apple steals your phone. Not worth it. They could still track it by IMEI when it connects to a network.