The problem is, of course, that it’s NOT human-to-human communication. It’s machine-to-machine communication, and human-to-machine communication, and DNS was designed to create a mnemonic representation of a way to reach a machine.
“Hey, tiger’s down!”
“Hey, one nine two dot one six eight dot one oh three dot two five three’s down!”
(Even if you take an example with 192.168 being where ALL the addresses in the network come from: “Hey, one oh three dot two five three’s down!”)
In order for the machine to be able to determine what to do, it must be programmed by the humans that created it. In order for the machine to be able to determine what to do in a situation that has more than one possibly-correct resolution, it must be given a set of rules in order to determine what needs to be done.
I will admit that it is possible (not plausible, but possible) for even an email system to be programmed with enough intelligence to be able to deal with the conflict. However, the key word is ‘system’ – defined as “all pieces in a computing environment that contribute to a given piece of data being processed the way the humans that are using it desire it to be processed.” Which includes all mail servers (speaking SMTP), as well as all mail clients (speaking SMTP, POP3, IMAP, whatever else), and name resolution (DNS, /etc/hosts, NIS, whatever else), and even the underlying virtual circuit technology (TCP/IPv). The entire system must be programmed in a way that is consistent with how the user wants it to work… and getting even two sites to upgrade to a newer version of sendmail at the same time is difficult at best. Much less to get two sites to change their DNS configuration at the same time.
The point is: In order to do our jobs, we have to simplify these complex systems we’re responsible for as much as possible. At least with a globally-shared root zone, we’re removing THAT piece of complexity from the equation so we can determine what needs to be done at a higher level.
(Am I lazy? Perhaps. But I’d rather be lazy than crazy.)
Speaking for himself, not for his company.