All naming systems start with some context; otherwise they'd be trying to
impose a tree structure on the entire universe. restricting DNS URNs
to the real DNS is a reasonable design compromise.
Agreed.
The part I obviously am unable to get caffeinated enough to understand is
what purpose the timestamps serve -
A URN is supposed to be uniquely bound to a single resource for all time.
however a DNS name is not uniquely bound to an assigning entity for all time.
say party A holds example.com at time T1, and
party B holds example.com at time T2.
if there is a URN scheme based on DNS names without timestamps, then
unless A and B explciitly coordinate, there's a chance of a collision
between names assigned by A using example.com and names assigned by
B using example.com. but if the scheme requires DNS name owners to
include a timestamp in a uniform format, then A uses
URN:dns:example.com:T1 and B uses URN:dns:example.com:T2 .
also if you're trying to resolve those URNs, it helps if there's an
easy way to distinguish names assigned by A and those assigned by B.
the timestamp doesn't have any significance for the resource itself -
it's just a way of disambiguating potentially-conflicting uses of the
same domain name.