Bartłomiej Piotrowski commented:
When we talked about it last time on chat.gnome.org, I and @alatiera mentioned you don't really need systemd to launch D-Bus inside the container. I don't really think podman is "optimized" more than regular Docker to run systemd – it's just considered anti-pattern regardless of the tool and top of that, having to maintain custom executor is at least problematic for us given we almost never had an abundance of free time to spend it on non-standard solutions.