CentOS. We were stuck on an old version at work. The OS is already designed to use old packages for security/stability, so imagine how outdated they are on an old version. It was a nightmare getting new software running on it. That coupled with the other news surrounding CentOS and RHEL, I'm not touching those anymore w a 10 foot pole. I wish it just crumbles and Debian takes over. I have had amazing success with like 20 years on Debian and it just gets better and better.
Not sure you can really blame an OS that is out of support and that you should have upgraded to the new version years prior. I used CentOS in an enterprise environment for close to 10 years and really had no problems, except when we tried to shoehorn new software onto old versions it had no business being on instead of just upgrading.
I remember the upgrade from CentOS 6 to 7. It changed a bunch of stuff including making systemd the default init system. I'm assuming your company just wanted to avoid doing that work? But at the same time most other distros were switching to systemd so you would have had to do that work regardless.