I think the argument is more the IMEI side of things, one might naively expect that they could could simply change SIM and that would change ones identity and that anything like an IMEI could be easily configurable like how a MAC is on a NIC is.
IMEI is needed to allow them to identify the device's capabilities, and know if it's been reported stolen.
IMEI is needed to allow them to identify the device's capabilities, and know if it's been reported stolen.