Systemd manages daemons. Sshd is a daemon. It knows when sshd has finished starting up, in case something else is waiting on that, and if it dies, and whether it needs to be shut down. If systemd didn't do it, something else would.
That is not to say systemd isn't a hypertrophied pig, but it does do important work.
That is not to say systemd isn't a hypertrophied pig, but it does do important work.