It's been a while for me contributing - but had some time. Great discussion, a few things, Ubuntu is not just for desktops it is the leading web server instance used in website services. It over took Debian as the leading web server a few years ago. About 8 years ago CentOS used to be number 2 behind Debian but they were overtaken by Ubuntu. For web servers RedHat (RHEL) has never been closer than a distant 3rd.
RedHat (after IBM bought them out) have slowly turned into the Microsoft of Linux. Most of there products are now behind a paywall and their service agreement that you sign to use there work allows them to pull their product and service license from you. They are infringing on the GPL licensing setup by Linus and the Free Software Foundation (Stallman) and the Linux Foundation They are trying to choke out the downstream competitors to their distro (CentOS, Alma, Rocky etc.).
https://www.jeffgeerling.com/blog/2023/im-done-red-hat-enterprise-linux
When I was at GoDaddy their Dell servers ran CentOS 7 and they were probably ranked in the top 4th largest datacenter providers in the world for webservers.
For services other then web services RHEL is still probably the leading Linux instance that runs on bare metal in the data centers at the enterprise level. However keep in mind the largest datacenter cloud provider in the world AWS, runs mainly their own Linux distro based off of Ubuntu/Debian. I have worked for large enterprise companies and clients for the past 11 years, companies with billions in infrastructure costs and I can say the we have implemented as many Debian, and Ubuntu based servers as we have CentOS and RHEL boxes.
Canonical (The owners of Ubuntu) Also have a lot of dealings with Microsoft. They were the first distro to be available on MS WSL. And as you know Ubuntu is based on Debian's unstable branch.
Where does that leave the average users of Linux for server based services. My opinion is squarely with Debian. Debian of all of the distros is the oldest and has remained the most constant. There are only really 3 MAIN foundational distributions of Linux left, Debian, Fedora, and Arch, All popular enterprise implementations of Linux come from either Fedora, or Debian. But Fedora is a bleeding edge distro not considered stable for enterprise use RHEL is the downstream stable version. Only Debian has a stable version, that is considered enterprise ready, maintained and free for use.
3 more observations:
1. Servers need consistency - any kind of server service should be based on a minimal, well maintained, stable OS. You want to maintain security patches and minimal updates that don't break your implementation. You don't want every new bell and whistle out their. That means a server distro (Ubuntu server, or Debian bookworm). Most server instances are implemented and maintained headless - accessed through the CLI and don't have a desktop environments installed.
2. Containerization (Docker) is a double edged sword - It can seem easy but there are also trade-offs that have to be taken into consideration, like root usage, networking and non-ephemeral storage considerations. Sometimes you aren't making things simpler, you are just trading one set of complex issues for another. Also mostly headless.
3. Servers require admin knowledge - There is no easy fix or solution to maintaining even a simple web server in a secure state. There will always be issues of maintaining the PHP/Java/Node/Golang/Python language base on the system and there will always be dependencies of the language, framework, daemons, and configuration that are not part of the base distro's implementation and that have to be tweaked and updated for your needed uses case. It is part of the job.
In most cases it is a choice of learning to DYI the stuff or paying a hosting company to take care of it for you. Thus the explosion of positions in companies such as DevOps, Platform, and Site Reliability engineers.