We needed fedora coreos. OpenShift used RHEL CoreOS. It took longer for fedora coreos because we also wanted fedora coreos to be a sufficient replacement for ContainerLinux. That integration started passing CI with openshift today.

Readme updates and lots of this stuff need to be done - we left the readme at 3.11 because that was a coherent install (vs the more work in progress of fedora coreos).

Every bit of source code was there (and developed in the open), but it wasn’t all “pulled together”

Clayton already answered some of this, but I also have some other ways of saying the same thing.

OKD 4 uses Fedora CoreOS for the same reason that OKD 3.11 used CentOS instead of RHEL. For better or worse, they're built and maintained by different systems and/or people, and we simply can't just make OKD use a RHEL derivative due to how support and subscriptions work.

Functionally, they should be nearly identical, but in practice, they're two different pieces of software and they're maintained and built in different systems, much like how Fedora, and CentOS are managed separately from RHEL. The differences mostly come to where packages come from and what systems built them.

The code for OCP/OKD is the same, the major difference is how it's built and released and the OS (RHEL CoreOS vs Fedora CoreOS), and potentially the upgrade graphs supported via over the air updates.

As to who Clayton is: he is basically one of the the main architects for Openshift since basically the beginning (I forget if it goes back to prior to v3).