File tracking

You don't want to create files in postinstall that won't be in the dpkg/rpm file list since it's good to be able to use rpm -qf /file or dpkg -S /file.
Generally, you don't want to rely on pre/postinstalls to manage symlinks like /etc/rc3.d/S10startdaemon. The order of install/remove/trigger run/pre/postinstalls + inter package triggers is fiendishly complicated at times. We just made the symlinks part of the package itself, and we know for sure they get removed if we remove the package.

You don't want to create files in postinstall that won't be in the dpkg/rpm file list since it's good to be able to use rpm -qf /file or dpkg -S /file.