Actually, they are getting rid of that requirement:
8.The requirement for operational service from two DNS servers has been deleted.
http://rs.internic.net/domain-info/nic-rev03.html dan On Wed, 11 Feb 1998, Michael K. Sanders wrote:
In message <19980211132424.19891@dragonlair.dal.net>, Dalvenjah FoxFire writes:
I'm posting here because I feel it is an operational issue; that, plus I feel there're more folks here who can and will hammer at InterNIC to start doing something to enforce their policies that require real, authoritative nameservers.
If nothing else, it might deter casual domain speculators. God forbid they actually have to configure something before they can register a domain... No doubt someone would just automate the process, though.