Systemd is a collection of low-level system utilities. Its primary responsibility is managing services and serving as the init process (PID 1, the first userspace process started by the kernel), but it also has other components, like systemd-boot (a boot loader and GRUB alternative), journald (system logging), networkd (network interface management), resolved (DNS resolver), or udevd (manages device files in /dev).

People tend to vilify systemd because it is maintained by Red Hat, a company with many controversies, and a pariah among the more extreme FOSS enthusiasts; and because it’s seen as bad practice to have a single entity be responsible for so many low-level system components.

Note: the -d suffix is not exclusive to systemd things. It simply marks the program as a daemon, a long-running background process that provides some kind of service. For example, sshd (SSH server) or httpd (Apache server on some distros) are not parts of systemd.

To answer your question: not really. As far as I know, the network interface won’t have an IP address unless the computer is turned on. If you use a timer (or any other method for that matter) to power on the computer, it will request an address from DHCP as soon as the interface is brought up (unless it has a static address).

A more practical application would be scheduling long, unattended tasks, like updates or making backups.