Ok, there could be no reason for network addresses to be scarce, but they 'are' scarce, mainly because it's easier to manage a scarce space for us humans. And simpler.

The point here is that there's actually no reason to have a public address in every internet connected device!
Actually, I'd argue that it's better to not have a public address in every device.

IPv4 is pushing for decentralization of the address space! ☺️ 💪