The first argument is also a limitation of HN and an opportunity for alternatives. Actually maybe even the first two.

HN community, culture and politics (and also its moderation) are very Silicon Valley / US centric. This comes through especially on non-technical (but relevant) topics, like regulation. But also topics like company culture are extremely US-centric.

Localized topics (both in terms of content and culture) is probably the only reason why an HN-like site would be viable.

From my perspective it's definitely desirable, and just the current frontpage of technews.london confirms that there is a lot of stuff that will never make it to SV-centric HN.