Ah, that is an interesting point. I think I see what you mean.
In my mind, L2 addresses are not for routing across organizations, and L3 addresses are. So the L2 address identifies an interface, and a L3 address identifies a routable entity. The weird thing is that there is an almost one-to-one mapping between these.
It might make sense for the same host on e.g. a WiFi and Ethernet interface off the same organization to have the same L3 address. After all, the organization responsible for routing to that host can know those interfaces belong to the same host.
However, once you get into multiple interfaces at disparate organizations things change. Take for example, a phone with LTE from some provider and WiFi from some how ISP. There are two separate organizations who are responsible for routing to those interfaces. Hence, the decisions needed to route to those interfaces differ. This makes routing based on the same address a lot harder.
I think my argument boils down to "topology follows addressing" being highly beneficial in our federated world of routing on the internet. It allows every autonomous network to handle internal routing however they want.
In my mind, L2 addresses are not for routing across organizations, and L3 addresses are. So the L2 address identifies an interface, and a L3 address identifies a routable entity. The weird thing is that there is an almost one-to-one mapping between these.
It might make sense for the same host on e.g. a WiFi and Ethernet interface off the same organization to have the same L3 address. After all, the organization responsible for routing to that host can know those interfaces belong to the same host.
However, once you get into multiple interfaces at disparate organizations things change. Take for example, a phone with LTE from some provider and WiFi from some how ISP. There are two separate organizations who are responsible for routing to those interfaces. Hence, the decisions needed to route to those interfaces differ. This makes routing based on the same address a lot harder.
I think my argument boils down to "topology follows addressing" being highly beneficial in our federated world of routing on the internet. It allows every autonomous network to handle internal routing however they want.