Systemd is more than an init system. Systemd was designed to be different from previous Unix-style single-/narrow-purpose services. Many distros making the switch seems to indicate that such a switch had significant enough upsides or necessities. No?

I read an article about why Systemd became what it is, and why it makes sense, and that made sense to me. Integration and a fully designed system has advantages over disconnected utilities and systems you have to connect and negotiate, especially on system- and boot-up level concerns.