Some bots are trying to influence conversations on some topic, and they comment on neutral topics to build up karma or whatever.

Also, some people are weirdos.

There are HN accounts that have been shadow-banned for years, and yet they keep posting despite few people ever seeing their posts. They're not LLMs AFAICT, but they just keep posting into the void.

So why use an LLM for commenting? See above, people are weird.

Marketing and influcence.

For example, consider this prompt -- "Find topics that would be relevant to people interested in <company> and post a topical post that mentions <product>".

Also, influencing public opinion on certain topics, such as Israel or Palestine, the current administration, the democrats, the various wars that are ongoing, or AI itself.