Is it though? Almost all the guidelines are curt and open to interpretation. For example, what counts as snarky? What counts as kind? Is there some hidden arbiter in between the characters I can't see? Not everyone will know exactly what these mean in every situation.
In truth, the rules here are intentionally vague, so they can be used as a cudgel by people who don't like what they read. For the mods it's for behavioral control, and for the users it's for thought control. The mods want the website to be a financial tool for YC, and the users want all opinions to mirror their own. But HN is built awkwardly, and forces too many different kinds of users into one tiny space. So the mods do what they can to remove submissions and kill comments, to make the appearance of some kind of nerd chat gestalt. This thread is an example of that failed attempt at enforced harmony. You can't punish people into electing to behave the way you want, it just makes them angry.
I suspect if you show this thread to enough random people, a clear majority opinion will form on whether that comment was snarky and unkind. The language in the Guidelines isn’t objective, but I also don’t think it’s all that difficult to understand if you were taught the difference between being forthright and being sarcastic, and the difference between being gracious and being unkind.
Of course some people will get angry and defensive when they cross the lines and get called out on it. That’s just human nature. (YouTube is chock full of examples.)
It doesn’t mean enforcement isn’t necessary, though. The owners have made it clear that they don’t want this site to devolve into a free-for-all full of sniping and bile. Their house, their rules. Want to be a dick? There are other venues for that.