On RHEL 8 docker didn't support cgroups v2 so the OOTB `docker` package installed podman and aliased it to docker. IIRC Fedora 30 and 31 did too? I don't remember exactly.
You can run docker pretty easily on RHEL 8 but you have to downgrade cgroups in order to do so. Plenty of guides out there now.
Yes current docker does, but it didn't at the time RHEL 8 came out. The question I was responding to was "How did you get podman instead of docker installed in the first place?" and GP mentioned `dnf`, which is a RHEL/Fedora thing, so I think it's a pretty reasonable theory.
