- an institution can publish a report as part of a regular schedule (e.g. unemployment by the BLS) or as one shot thing (e.g. a study on clowns distribution in arid areas). This leads many reporters to publish articles about basically the same subject, but in an uncoordinated manner;  

 - PR agencies often coordinate with media outlets from various backgrounds and markets to publish about some particular topic (company, product, campaign, ...) either at the same time, or in coordinated waves;  

 - trends and public discourse can make it so that many sources cover almost the same thing at the same time (e.g.: bitch resting face, rat boy summer, ...);  

 - luck is, always, a factor.

- tech-oriented publicists / marketers definitely do know that HN exists and matters

- there are “benign” ways to game HN, like releasing at an optimal time for readership / upvotes

- there are less nice ways, like sock puppet accounts / botting

- all of these things are certainly done regularly

- it doesn’t mean that everything you read was an astroturfed psy-op or whatever.

I recently saw a xeet, from a columnist, complaining about irrelevant PR pitches; it gives some insight into how they work. See: https://x.com/dhume/status/1892994787734602001

>Of the stories you read in traditional media that aren't about politics, crimes, or disasters, more than half probably come from PR firms.

https://paulgraham.com/submarine.html