If I’m understanding correctly, you’re saying that right now the network doesn’t have an exhaustive table of IP addresses to physical locations. It has a cache, and a hierarchy, and the path to a location of the IP is fluid.

But a system where every device could be directly contacted/identified like a Sim card, would effectively require a complete table of “what network is device ABC at”. A table that is updated every time the device changes network connections. It would be like trying to change domain name to point to a different IP address.

The problem is, updating a domain to point to a new IP takes hours or days not seconds, so doing that every time a phone changes WiFi is not practical.

Is that a good summary?