It’s because you now need to do systemctl restart sshd instead of /etc/init.d/sshd restart, I see no other reason than having to learn new syntax.

Arguably, init.d scripts were easier to understand, and systemd is a bit of a black box, it somehow works, but who knows where it writes logs or saves the process pid (it’s all in the documentation somewhere), with init.d script you can just open the script itself and look.