HN is perfectly usable without JavaScript enabled.
The only feature that appears to require JavaScript is search.
Which doesn't even make sense. You don't need JS to trigger a form with a GET method, nor do you need JS to render the serve response to that GET.
AFAIK, search is really a place for Algolia to show off its API based search services to the HN audience, not really just built to be a simple static page search result to match the HN architecture.