It's not that irrelevant, considering that podman managed to solve both problems - necessity of a daemon and keeping the default network namespace clean. That said, I don't want to take away the credit of Docker being the pioneers in their field (yes it existed before. But it wasn't this popular).

Isn't Podman only able to do this because of user namespaces, which are a very recent addition to Linux? I wonder how Podman will do, if that's the case, now that user namespaces are being turned off by default due to their security implications.

I always thought containerization - including docker - was the result of Linux namespaces (more so than even cgroups). Checking again, Linux namespaces were introduced in 2002. Docker was released more than a decade later - in 2013. I believe that Docker always used namespaces - that's how they achieved process isolation. But they didn't use it to its full potential initially - including network namespaces and pods.

Unprivileged user namespaces are much newer.

Thanks for mentioning that.