Master DNS in SOA not found?

[DesignGuy]

"Jonathan de Boyne Pollard" <J.deBoynePollard at Tesco.NET> wrote in message
news:ccf7dg$2i94$1 at sf1.isc.org...
> D> Making changes to the file seems to have no effect as far as the
> D> domain check reports go.
>
> What made you think that it would ?  The DNS data for your domain are
> published to the world by content DNS servers owned and run by a DNS
hosting
> company (ThePlanet) that you are paying to do this.  Why do you think that
> changing the DNS database content on your own entirely separate content
DNS
> server will have any effect at all on what data the rest of Internet
> (including the organizations that provide the free DNS checking services
that
> you are using) sees ?

Then why is that file there if it serves no purpose?