[blunte]

That's the problem though... the post I saw wasn't flag-worthy. It was a bit poor quality in my opinion, but it wasn't objectionable.

What was obvious to me was the frequency of submissions of the account, and additionally nature of the topics.

Simplistically, I would question the need for any HN user to submit more than one or two entries per day. People who submit 10+ are probably suspect.

[hillcrestenigma]

Maybe there needs to be a way to flag a user if they are negatively contributing to HN.

[version_five]

There is. There is banning and shadowbanning, which includes mechanisms where whatever stories someone posts are "dead" on arrival. HN has robust mechanisms against spam. Re "manipulation" I'd think one person's manipulation is another person's posting interesting stories, but as was said, if someone's submissions get flagged enough, it will get attention and their posts will be killed if deemed spam. Overall I think it's more common just to see posts that people disagree with or read into versus actual "manipulation".

Also, the concept of manipulation is very insulting to the readership. Maybe it's sometimes warranted, but on HN of all places, I think people can debate, judge, and flag on their own if they think something is being manipulative.