What I learned while securing Ubuntu (2015)
And that is a major reason military and lots of enterprise customers run on RHEL. It is this seemingly uncool and boring stuff like having STIGs, FIPS-140-2 certifications, EAL-4  etc.And it spreads like a virus in a way. Say you use Alpine / Gentoo / Ubuntu. You get your first enterprise or DOD customer. They want an onprem version of your service. Now you have to either not sell it o them (but it so happens those customers also come with loads of cash willing to drop it in your lap). Or support both RHEL and Ubunu. So after a while you start to wonder, why bother supporting both, so you switch to CentOS/ RHEL stack only.I've seen it happen, people grumbled and were angry, but they still would rather have loads of cash dropped in their laps than stick to their preferred OS.A couple of years back. Remember Mark Shuttleworth inquiring about what would it take for Ubuntu to get some uptake with US govt customers. Remember emailing him a list of some of those requirements and yeah, it is very expensive and time consuming to get those red tape stamps on your product. I don't know if anything happened with Ubuntu in that regard since.(You can also get exceptions depending on who you sell to, but it only happens if you have friends in high places which can grant those. Say sell to special ops teams, for example).