I have spent many hours looking at this. From the data I've seen, there's zero evidence to back up the accusations of political astroturfing, shilling, and spying that users make against each other on HN, and plenty of evidence against it [1]. The only actual observable pattern is users posting comments that disagree with one another. Anything beyond that is an interpretation. I have not seen any data to support those interpretations [2].
When it comes to users accusing each other of astroturfing, shilling, spying, and so on, the only conclusion that fits the data is that people are imagining things. In reality, the community is simply divided and users have opposing views. Unfortunately, when my view is sufficiently obnoxious to your side or vice versa, the assumption of good faith evaporates and people reach for more sinister explanations. We can speculate about why, but it's clear that users are projecting those sinister explanations onto fellow users. The more divisive the topic, the more opposed people's views become and the more harshly they express them, leading to more projection, accusation, and division. A vicious loop.
This is especially toxic to HN because HN is a single community where everybody sees the same threads. Here you are more likely to run into views that you strongly dislike than you are on sites where communities partition into like-minded factions. Even when discussions on HN are more thoughtful than these other places, the fact that you're part of one big group—everybody, instead of mostly your own tribe—makes them feel less so.
When people post aggressive remarks to HN, they're not just bonding with their own tribe, they're simultaneously broadcasting to the other side, who take the harshness like a punch. All sides do this, so all sides feel punched. This is painful and one can't help but react internally. I believe that the accusatory reactions are self-protective. If you're a spy or a shill, that explains whatever you say and I needn't give it any credence. Unfortunately, these defensive reactions are also offensive ones, so we get an escalatory cycle. If HN is to avoid being ripped apart, we need a rule against such accusations. Therefore we do have such a rule.
1. There are other contexts on HN where we do find manipulation: usually startups or projects trying to promote themselves, but occasionally also more sophisticated astroturfing that appears to involve larger companies.
2. More on this at https://news.ycombinator.com/item?id=19403438. For a specific example, see https://news.ycombinator.com/item?id=19404162.
p.s. I'm sorry that felt like I was targeting you specifically. My intention was only to say something about a general phenomenon which I've written about many times already: https://hn.algolia.com/?sort=byDate&dateRange=all&type=comme....