I understand where you are coming from, but I think it is just a matter of framing. If you consider regular Ubuntu releases to be the "beta branch" of their LTS releases, then the comparison would be apt.

I don't really see it that way. Each Fedora release is reliable, but the software does evolve quickly. The RHEL releases are taken from a point in time on that stream, pushed through an even more extensive QE process, and maintained for an extended period of time.

But Ubuntu doesn't say that they use Ubuntu as "... an ideal incubator and proving ground for features."

I use to use Fedora Core and then up to Fedora 7. I got burned way to many times and view Fedora as a slight step up from Arch Linux as a working distro. Both Fedora and Arch are more "hobbyist" distros and I will not use them in a professional work flow. I use OpenSUSE and I find their model to be the best of Distros and haven't ever got burned by them. OUTSIDE of 2001 when I was installing SUSE and wiped my partitions because I didn't know what I was doing :)

You can read from that excerpt whatever you want, but it still does not make Fedora beta for RHEL.

Just like Windows 10 is not beta for Windows LTSB, or Linux kernel releases are not betas for kernels that will be LTS.

Based on your comment I assume you're an old timer. It's been 14 years since the bad blood days of Fedora Core 1. Fedora is way more polished than back in the day.

Yes, I am an old timer, but Fedora still isn't production ready like Ubuntu, OpenSUSE or the paid for distros. I am certainly more of a pragmatic Linux user so the graphic card drivers are not proprietary blobs and must use the open source drivers. I might be wrong haven't installed Fedora since 14.