Mainly selected podman for the security, it doesn’t rely on a daemon and supported rootless containers before docker did. Easy to just come up with a pattern where you can minimise the risk of container breakout by having a user for each container stack to provide even more isolation. You can do the same with docker these days I think, each user just runs their own copy of the docker daemon. The aim of the project was to achieve 1:1 compatibility, I think it’s pretty close these days. It’s also native to the Redhat family so could avoid using the community edition of Docker.