Hm, strange, HN seems to set referrer-policy to 'origin', which seems like it should send a referer header when going to external sites[0]? But clearly it does not. So I guess I'm just misunderstanding how that header works.
Asahi and a few other websites blocked HN traffic (because of the aforementioned problems) and then HN added special nofollow/noreferrer for only these domains to prevent this. and then the sites responded with more assertive measures.
This is incorrect. These sites (or at least the Asahi one) are not being "assertive" - they are being hypocritical and toxic.
Additionally, nobody has the right to selectively block links to their website. You get two options: you either let your site be publicly-viewable, with all the benefits and drawbacks, or you make it members-only and require a login. You can't have your cake and eat it too.
[0] https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Re...