"Really Important Things" are usually business-internal software (for example, there are likely thousands upon thousands of perl scripts mangling data for company systems, where the original developer is long gone but they continue to work). Developer time spent on that doesn't really benefit the community as a whole beyond a blog post here and there about some aspect of how to set it up.

And when that software breaks on an OS update (say CentOS 6 -> 8) is when often "virtualize that machine and keep running the old code" becomes the answer.