Registrars: The Internet's Travel Agents?

On the ALAC list, Evan Leibovitch writes:

I see registrars in much the same way as I see travel agents -- they are useful for some, but not all consumers (and not all suppliers) need them.

Once travel agents were a mandatory middle step while airline competition was minimal. But as the regulations have been lifted and there are more airlines, the marketplace has benefited from travel agents becoming optional, as airlines are able to act as their own booking agents. And nobody complains about the ability of airlines to change fares -- from minute to minute -- as specific routes become more or less scarce.