> Further, because you don't have only one external IP, you don't have to futz around with non-default ports if you want multiple instances of the same service (e.g., Minecraft), because each instance can have its own IP.

This is an interesting point though personally I love how easy container technologies made exposing arbitrary ports, without trying to configure the software itself, or checking whether it even supports customizing the port.

For example, I could have 3 database instances, each using 3306, but expose them on 30000, 30001 and 30002 or whatever I want.