The MAC address is meaningful only for a single link. It doesn't get copied through routers and get carried along to the destination. (At least in theory. Between software defined network hardware and enterprise WiFi, there are cases where MAC addresses have wider scope. But they rarely leave an organization.)
The Xerox plan for Ethernet was to use XNS, with a 32-bit network ID and a 48-bit MAC. Routers only had to know how to find a network ID, and once the packet hit the correct destination network, the MAC address routed it to the destination.
Early on, there was a thing for "multi-protocol routers", that forwarded XNS, DECnet, IP, and a few other things such as Parc Universal Protocol, PUP. Cisco was once big on this, because Cisco came out of Stanford, which had a few of everything and tried to interconnect them.
In the 1990s, most of those branded protocols died out, although as late as Windows 2000, Microsoft still supported TP4, a bad idea from circuit-oriented telco people. There was a telco approach to networking, where you dialed up a reliable circuit to your destination, transmitted what you had to send, and later got a bill for the call. This, fortunately, lost out to IP.
(I had real doubts about pure datagram long distance networks. We didn't know how to deal with congestion in the middle of a pure datagram network. We still don't, but cheap fiber saved us from having to.)
The Xerox plan for Ethernet was to use XNS, with a 32-bit network ID and a 48-bit MAC. Routers only had to know how to find a network ID, and once the packet hit the correct destination network, the MAC address routed it to the destination.
Early on, there was a thing for "multi-protocol routers", that forwarded XNS, DECnet, IP, and a few other things such as Parc Universal Protocol, PUP. Cisco was once big on this, because Cisco came out of Stanford, which had a few of everything and tried to interconnect them. In the 1990s, most of those branded protocols died out, although as late as Windows 2000, Microsoft still supported TP4, a bad idea from circuit-oriented telco people. There was a telco approach to networking, where you dialed up a reliable circuit to your destination, transmitted what you had to send, and later got a bill for the call. This, fortunately, lost out to IP.
(I had real doubts about pure datagram long distance networks. We didn't know how to deal with congestion in the middle of a pure datagram network. We still don't, but cheap fiber saved us from having to.)