That's no denial. That guideline specifically asks people to notify us so we can investigate. We do that every time anyone asks. I've personally spent hundreds (probably thousands) of hours investigating such things, have banned many accounts and sites for it, and have put tons of effort into writing code to combat it. We take it seriously. We just need some evidence. Surely you don't think we should lower the bar below that?
If you don't believe me, ask troydavis, who went to all the trouble of investigating the above case and writing the OP, whether we take evidence seriously and ban accounts and sites based on it. Or any of the countless other HN users who spot things and ask us to look into them. They're the ones who actually care enough about the community to help protect it.
The problem is that there's another side of the coin: most of the cheap insinuations of astroturfing, shilling, foreign-agenting, spying, botting, and all the rest of it—where by "most" I mean the vast majority—are pulled (begging your pardon) purely out of the insinuator's ass. Internet users just love to make this stuff up as a cheap way of throwing shade on whatever they dislike. That's the dross the guidelines ask HN users to keep out of the threads. This is important because gratuitously accusing others of dishonesty is a fast track to poisoning community, and it's 1000x easier to generate such accusations than it is to answer them.
> This is because these sites realize the exact opposite. That the percentage of this stuff is absolutely massive and they are terrified what will happen if the public finds out how common it is.
Here is something I can answer definitively—you're talking about what's going on in my mind and I think I can speak with some authority about that. No, that is not what's happening. What's happening is that I worry about the integrity of the community on two sides: protecting it from actual abuse and manipulation on the one hand, and protecting it from toxic fantasy bullshit on the other.