Doesn't this objection also apply to passing an FQDN around,
since FQDNs can also be unreachable, due to 2-faced DNS
and the like?
What would be the logic of making something unreachable using twofaced
DNS? I thought the point was to make sure that different people connect
to different hosts when they try to connect to an FQDN. The situation
where one side of the DNS produces something useful while the other
doesn't is either unintended, which is the risk you run by abusing
technology in this way, or is intended in which case there isn't a
problem.