The point of OP's link is that the novelty of systemd is that you can compose chains of dependencies and how that saves time and effort.

So why should it be a common operation for the enduser to start and stop a list of related services? Instead of having to type and remember them individually, I should add a BindTo line in my service files and let systemd handle it. It's like the frontend for systemd is optimizing for a situation that it is supposed to prevent.

And anyway, there's no unixy reason the variadic argument couldn't be in the middle. cp, for example, has

    <command name> <options> <variadic list of files to copy> <single dir to copy to>