First two sentences are key. The reason why HN is so much better than other fora (IMO) is that the mods don't allow lever-pulling and astroturfing to overtake regular contributions. Yet it's also popular, so you're bound to get some activity on most posts.
Sure, it can be frustrating if you're trying to promote a product or farm karma on posts. But the fact that mostly nobody cares about karma means that you can post something and have it be evaluated on its technical, economic, social merits.
Obviously, there are caveats to this - i.e., anything US- and FAANG-related is bound to get much more activity than otherwise - but the overall atmosphere of HN is refreshing compared to Reddit.
I can't know for sure. For me, it's just the "eyeball method" of comparing HN and different subreddits on Reddit.
As to how I (or anyone) could show this, here are a few example questions:
1. How many examples of stealthy but otherwise blatant promotion do you see in the comments? Not every astroturfing campaign will be successful or original, so you'd be able to notice some patterns. Plus, HN is already commercially oriented, and there's the "Show HN" option, so it reduces the incentives for astroturfing.
2. Alternatively, how much controversy is there around the specific type of forum? For some subreddits, for example, you'd be able to see counter-subreddits popping up when participants feel the mods are abusing their power to promote one type of opinion.
3. Is a certain type of political/brand-related opinion or interpretation always at the top of your comment feed? For example, if upvotes determine the order of the comments, do you consistently see fewer critical comments on things that you'd expect the community to react to in different ways.
4. Do you consistently see some contributors having more power in discussions over others? Other than the mods, obviously. If this is the case, karma (i.e., number of upvotes) often has more value.
I'd be shocked if it were because the owners now this is a fragile thing and one word from Dan or Tom that this is or was the case and half the participants here would walk. The owners are more than likely well aware of that risk and are not going to destroy the goose that lays the golden eggs.
Check out the treatment PG (and Garry Tan) got in the thread about defending YC's effective investment into Installmonetizer for a good example of news.ycombinator.com's response to such crap.
Sure, it can be frustrating if you're trying to promote a product or farm karma on posts. But the fact that mostly nobody cares about karma means that you can post something and have it be evaluated on its technical, economic, social merits.
Obviously, there are caveats to this - i.e., anything US- and FAANG-related is bound to get much more activity than otherwise - but the overall atmosphere of HN is refreshing compared to Reddit.