You can perform automated installations using a CD or DVD, but you will need physical access to the machine in order to put in the media, tell the system to boot from the media, and possibly start the installation.

Additionally, regardless of whether you use a distribution that uses kickstart, preseed or autoyast, you would either need to include the automated installation configuration file on the media or make it available in a central location and edit the isolinux menu to perform the installation procedure using that kickstart file.

Updating the kickstart file if you have put it on the media would mean you would have to burn the media each time you change the kickstart file, which isn't very efficient nor flexible.

When putting the kickstart in a central location like a webserver, you eliminate that one single factor that causes you to burn and burn again the ISO to disc, but does not allow you to create several menu entries corresponding to different installation profiles, or you would have to burn the updated ISO once more, making it less efficient then the PXE alternative.

Alternatively, you would manually type the URI to the automated installation configuration file whenever you boot and want to install a system.