That level of backwards compatiblity with legacy versions exists on other platforms (Windows, z/OS, AIX), especially those implemented in enterprise environment

That level of backwards compatiblity with legacy versions exists on other platforms (Windows, z/OS, AIX), especially those implemented in enterprise environments. If I have a Windows app written in Win32 API, it'll run on Windows 11 on 64-bit architecture. That's what companies want. That's how Linux became viable for those customers. Even Edge has an IE mode because that's what enterprise environments need, support for older libraries and APIs. I won't deny RHEL was higher technical debt for sure, but that was the trade off, because that's what enterprises prioritized, support, stability, and knowledge that an update during their monthly patch cycle and change window for rebooting the server won't break the business applications they rely on for fundamental operations, at least not on the same major release version. 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.