The only use case I encountered is people who want to run Docker without root or admin permissions and use Podman just as a drop-in replacement.
It lets you define a systemd job with some custom syntax and run it as a systemd service, and even stretches to allow some form of kubernetes YAML to be run as local (single node, rootless) containers!
Real nice.
See previous presentation on HN: https://news.ycombinator.com/item?id=43456934
_But why?_
I mean, if you have one container service only and everything else is ran by systemd, then it makes sense to keep it easy. But other than that, why? Systemd's syntax and docs aren't particularly friendly or easy, so it's not like you gain in simplicity vs just running docker/podman-compose, or even a lightweight orchestrator like Nomad.
- seamless container logs (journalctl), no weird separate logger
- service start/stop/enable-at-boot no weird separate command
- integration with system/user slices, triggers, cronjobs (timers), exposing containers as first class commands overall!
Basically it's worth seeing container services work with non-container services.
If you don't like systemd, or have no stake in it, sure, have fun without it, but it's definitely added value when you're running services, and want to start containerizing some of them without abandoning all the good tools you are using in favour of docker logs docker run etc.