Devuan is the outlet of a bunch of people that don't want Linux to evolve, become better and have more flexibility because it violates the UNIX philosophy and/or it is backed by big corp. Systemd was made to tackle a bunch of issues with poorly integrated tools and old architectures that aren't as good as they used to be. If you look at other operating systems, even Apple has a better service manager (launchd).

Systemd is incredibly versatile and most people are unaware of its full potential. Apart from the obvious - start services - it can also run most of a base system with features such as networking (IPv4+IPV6, PBR), NTP, Timers (cron replacement), secure DNS resolutions, isolate processes, setup basic firewalls, port forwarding, centralize logging (in an easy way to query and read), monitor and restart services, detect hardware changes and react to them, mount filesystems, listen for connections in sockets and launch programs to handle incoming data, become your bootloader and... even run full fledged containers both privileged and non-privileged containers. Read this for more details: https://tadeubento.com/2023/systemd-hidden-gems-for-a-better-linux/

The question isn't "what is the benefit of removing this init system", it is "what I'll be missing if I remove it". Although it is possible to do all the above without Systemd, you'll end up with a lot of small integration pains and dozens of processes and different tools all wasting resources.