Most SELinux policies, Corosync and Pacemaker and related HA / clustering tools, and a pile of other things and they settled for a really awful stable kernel major in Jessie / 8.x.

It really went downhill with, the release of 8.0, the only improvement we really saw was a slightly newer kernel (but still old) and SystemD (although not consistantly implemented), The Debian community has also fallen through the floor, lots of smart-ass bickering and slack package maintainership and generally unhelpful, rude contributors / owners. By contrast RHEL/CentOS sped up their release cycles after re-in-housing Fedora as and taking a lot of it's rolling updates into stable a lot quicker and the community has been fantastic, Redhat have really stepped up and modernised their game a lot over the past two or there years.

I happen to run most of the latest of things on CentOS (server-side only, though). My approach has been to package and deliver modern versions of various runtimes (python, ruby, jre) into specific directories for my apps. This way, I am not dependent on the system-provided runtimes which are an older version.

For my work with Belenix (revamp not announced yet), I am working on examples where users no longer depend upon system-supplied package versions, and instead choose their own local instances.

Not sure what you mean, if RedHat/CentOS is good for Amazon to run their 2M linux nodes, it is probably good enough for me to host my services. The stability and production readiness of the platform beats all the other Linux distributions, especially Ubuntu and I would argue Debian too (hello purify complains bug).

CentOS only includes packages that Red Hat builds and supports on RHEL. Extra packages are maintained by the community as part of Fedora EPEL.