Why don't people make the effort to just move to Debian Stable? If you don't want to pay any money, relying on Redhat's goodwill always seemed precarious.
Because there's a big software stack from drivers to scientific software which is being developed for 10+ years (or even longer) for RH based distributions, or for CentOS/ScientificLinux specifically
Software development and verification is huge in scientific computing. It's not just "Meh, let's port it in a weekend and be done with it".
I think this applies to the whole community. For many years we just assumed we could runt CentOS forever. When RH bought them there was an initial shock but they quickly clarified CentOS is not going anywhere so we were happy. Now that it's gone I kind of regret I didn't insisted or at least kindly asked some vendors for Debian compatibility. I didn't because I didn't have to, an now we're all screwed.
Software development and verification is huge in scientific computing. It's not just "Meh, let's port it in a weekend and be done with it".