You couldn't argue that. If anything, the main function of the kernel would be to control the hardware.
Care to point out an example?
No. With the new approach, you issue systemctl disable network.target and carry on with your day.
Or even better, disable the actual services that you don't want to boot, because otherwise you might accidentally stop a service you did want to boot after all.
Stopping the inetd daemon is a horrible, hacky way of doing that and you should never even consider doing that as an option.
And that's what unit files are about. They are supposed to be cross-distribution,
and as far as I know there is nothing preventing other init systems from using them.