This tells us there is a whole world almost totally omitted from discussion on HN

It doesn't though, all it tells you is that it's missing from the headlines in the submissions.

"Enterprise" is discussed on HN too, but inside submissions that aren't exclusively about MS Sql Server. Try searching for some terms on the Algolia HN search, order by date and filter by comments and you'll find the subthreads/submissions where it's discussed :)