Is this a packaging bug?

[Tom Horsley]

I installed dovecot and postfix rpms on my system at work,
and they didn't create the local users in my local passwd
and group files.

Apparently, they didn't create the local users because
the yp server happened to have those same users defined
on it.

When I rebooted my system both postfix and dovecot failed
to start because yp wasn't up yet, so the users were not
defined.

Shouldn't packages like this always want to really create
real local users on they system doing the install?