The principle applies, though. If they want to release on a given day, especially a new product, they have to put it in other hands to some extent a few days before. There wouldn’t have been much of anything changed between RC21 and the final release.
I don’t think there were many changes between the final beta and the release version, other than the addition of the activation components. That is the majority of what we were working on at the very end.
As for grand release notes that show every change between v1.16 and v3.0—that would be next to impossible to itemise, and so vast that hardly anyone would find it useful. We’ve always just gone with “initial release” for the first of a major upgrade.