You don't seem to understand how SystemD actually works. The PID 1 is relatively simple -- it uses all sorts of separate (i.e. non-PID 1) helper processes to do all the heavy and complicated lifting.
And another thing I like about systemd:
- it groups into 1 single project: 1 single task (starting-up/seting-up things) that was spread accross way too many different project before.
Want to start a service during boot-up ? Put it into sysvinit. Except if it's a file system, then it goes into /etc/fstab. Or if it's not a *service* but like of an interface like your terminal that should go into inittab (Except on distribution which do THE EXACT SAME THING but in init.d anyway).
The thing which start is related to actual hardware? the you need to put it into hal, no way we replaced that with udev... except that a few distro put them any way in init.d and thus your hardware might not work when plugged after booting... unless you also duplicate some code into modprobe.conf's post-runs.
And what if conditions for your code to start isn't "boot-up" nor "plug-in" ?
Then put it into inted/tpcd if it's network triggered. Except for code that doesn't work there, because the service needs to be compiled to use libwrap to work this way. So then you'll have to run the service constantly and fumble around with ip filtering to enable/disable it on demand.
Or put it into cron if it's time triggered.
And you need to start a service and the periodically monitor it for failure, and restart and raise alert if it has failed? Well either use an entirely separate custom system like djbdns's daemontools. Or write your own monitoring solution by writing a ton of scripts which tap into all those different ways to start/stop stuff and hope that it works.
And don't get me started about initialising containers (limited fonctionnality, tons of script), brokering access rights around (not really used. lot of interface must run as root and drop privileges, or lot of interface must be world accessible), handling situation as missing configuration or drivers in a system that hasn't fully booted up to the point where the GUI works and the user can fix things from here (huge tons of scripting to achieve way to detect that Xorg is failing and to propose solution to fix drivers)
All this written in shell script which can have their own pitfalls, and every single system using a different syntax.
PID1 and its herd of helpers take care of setup/start/stop/teardown.
Want to do *something*? Write a systemd config file, and describe which trigger (boot, after another service has started, on network, by clock, on device plug, etc.) should start it.
You can even call legacy systems from within systemd (cron can be reimplemented as a systemd service that runs periodically and reads/executes crontab, etc.)
You can have an LXC that is quickly setup. In fact you can quickly create throw-away container to jail any service separately (systemd is the kind of infrastructure that can boot a dedicated LXC jail to run Skype into, with restriction correctly setup so that no hidden backdoor could spy on you).
You can have systemd handle brokering the necessary rights (to the point that plugin an USB stick and having the currently active user access to it isn't a nightmare anymore).
If anything the handling of setup/startup/stop/teardown WAS NOT "unixy" before, it was "have 384 different programme which all do a different part of one single task in subtly different ways".