shutdown, reboot, … are symlinks on multiple different systemd repos, I have no reason to believe that is not the systemd standard.
systemd is not moving all it does into a single binary, obviously. Others already mentioned that and a bit further up I mentioned some systemd components that can be isolated too.
GNU posix is one extreme, and busybox the other, and the accusation is that the core of systemd sits too close to busybox, and the other projects might too group together things into fewer binaries that used to be multiple independent commands.
As for the core, I think that constitutes: services, logging (journald), cron+anacron (timers), blocking (systemd-inhibit), and mount.
I am probably missing some there. Timers does not interfere with other cron, but it is there whether you like it or not. Those components also come bundled with otherwise optional linux features like cgroup which do complicate using other posix tools with systemd, as you get unexpected results (like nohup not working).
You probably mean daemon-reexec, which also does not restart services (it better not, would be really problematic if it did).
I do mean reload, which has uses, otherwise it wouldn’t even exist and services would simply always reload: You may not want to reload yet, but keep a working state of service definitions in systemd while editing things, similar to typing away in a code file in production without saving yet.
I don’t see why I would need to “save” all my service definitions to get a usable (non-spammy) mount back, especially when my mount isn’t even part of systemd. How does the message even get sent by mount when mount is not aware of systemd?
PS: systemd can replace my text editor over my cold dead body