1. RHEL was the first distro directed at enterprise deployment (meaning, strong preference of rock solid stability and predictability over constant churn). Which made it the only distro Dells and HPs of the world recognized and agreed to support.
2. RHEL was created on legacy of RedHat Linux, which was the best distro for non-hobbyist environments (from reproducible deployments to the breadth of packages available) - since 3.0.3 onwards. RedHat JUST. WORKED.
1. Debian always had more stability and predictability than Red Hat in practice. Too much so. The Dells and HPs of the world didn't recognize it because it was not a company.
2. My impression was again that Debian was technically better than RedHat in every way I might care about. We happily installed it at $work, and the experienced Unix sysadmins I knew could use RedHat but didn't like it so much.
IIRC Debian maintainers formed companies for that reason.
I was a Debian user because it suited me. It was obvious (to me at the time) that suits were going to choose RedHat, and we ran it a bit to have experience.
How wrong I was. Ubuntu made Debian every bit as much as a "choice of the suits" as Redhat.
There were plenty of people and small highly knowledgeable shops and academics that thought 6 hours fixing a bug after custom compiling a patch was fine and normal (and a RHEL subscription at least meant RedHat would have a team doing that part for you if absolutely necessary), but its not the way companies operated. RHEL at least meant whatever release was stable and an actual QA team put patches through their paces on various hardware and configurations (especially those enterprise high end server configs with special SCSI/RAID controllers, high end network cards, and other chipset other distros simply didn't have the means to test on). The QA/support team wasn't bug reports and guys on usenet going "it works for me, you should have gotten the exact same hardware I have, or be willing to go through the code and figure it out and patch it, and submit it to the source, like a good user should". Or tell you go back to Micro$oft if you want support for your storage controller that the kernel module for worked fine in the last version. Those were the zealots, the rest were sys admins with too much other things on their hands to do than deal with Slackware or whatever the hot distro was on distrowatch.
But I was a lot younger and didn't know a lot of what I do now, so was probably doing everything RPM wrong.
In some ways, RHEL is still like that, because popular packages are usually a major version or two behind if they're even there at all. You have to hunt down an EPEL that has whatever you need.
But I also realize my perspective was that of a hobbyist, not an enterprise sysadmin who was probably upgrading to well-known versions through known paths.
The first time I did a major version upgrade on Ubuntu, I was shocked it worked.
Computers of all stripes are more reliable now. In the late nineties I ran apache + mod-perl built from source.
We had a lot of problems, but I cannot recall ever having a problem with those two.
We tested every update, of course, but it was not a huge burden.
That's inbetween figuring out how to get things to compile and the dependencies of dependencies, etc.
I got Linux to work, but it was also a love hate relationship, when I got it working, it worked and worked for months, but I had almost a PTSD reaction when it was time to upgrade anything, I knew what was coming and I was afraid.
I managed to compile Gaim before I managed to install it from RPM packages.
Using Debian was a moment of pure epiphany.
Good times.
RHEL’s “support” should be seen as “your software will continue to run unmodified when on this system”, but is frequently interpreted as “this is a sane platform for current development”.
RHEL was never supposed to be the latest, I think even a every new major release they'd be on a kernel and library version that was 2 years behind but had been through its paces. IOW, it was a feature not a bug, and its what companies were paying for (their customers were boring legacy Fortune 500s not startups). As a business model, it was solid, and the most successful in the commercial market by far because it catered to their customers needs, even if they're not our own, even Ubuntu Server took pages from their book.
https://peps.python.org/pep-0513/
And the thing is I was being conservative about MS running half the planet. They had their grubby hooks in everything.
That half of the planet did not run....