@Suiseiseki @gentoobro @famfo Domains introduce an authority problem in their most common form.

They also introduce authentication problems as it is mostly not used in conjunction with key-addressing.

Effectively, user-configured petnames (ref: Zooko's Triangle) and key addressing as Yggdrassil does is the only sane way to communicate at the application level (yes the implication is that there's no sane way to use IPv4 as it cannot encode a sufficient key).

The keys need not be encoded in IPv6, the underlying transport layer may be abstracted. But applications should not concern themselves with routing details (unless they are specifically overlay network programs, of course).