For example they can see I posted a request to Hacker News on a specific time. Then it is a matter of finding all posts that were made around that timestamp to see what I wrote and what my username is.
I think this is a lot of work to do. Just ask some 3 letters agencies for some help on some malware or on some "router firmware bugs" to be exploited etc. They don't care about hacker news readers or posting comments (because this implies you must know the DNS first, etc). They care about botnets DDoS-ing your railway infrastructure, ransomware on hospitals, serious stuff that can lead the country to chaos.
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I think this is a lot of work to do. Just ask some 3 letters agencies for some help on some malware or on some "router firmware bugs" to be exploited etc. They don't care about hacker news readers or posting comments (because this implies you must know the DNS first, etc). They care about botnets DDoS-ing your railway infrastructure, ransomware on hospitals, serious stuff that can lead the country to chaos.
On hn everything is public so if you only have the time at which two or three posts where submitted you can find the user in question easily.