Isn't that what your own name does?
I guess the point here is a database lookup before the mail is delivered.
I've never heard of anyone being able to send mail to a person using only their name on an envelope.
You would have a unique "ID" which you can assign to any physical address. This is all you ever give out. If you move, you update one record, and your mail will come to the right place.
It's similar to a website. If HN moves to another server, everyone doesn't have to update their bookmarks to point to a new IP address. Instead, they visit the same URL as always, and it automatically sends everyone to the new IP.
<his nickname>@<division>.<company>.<country>
so it should have been fairly easy to route.