Earlier quoted context omitted.
You don't think it's changed? You've been here about as long as we have. At some point you can't rely on it being a noob illusion if a place actually does change. The guideline is not a magic incantation that prevents it from never becoming false. Snarky replies used to be routinely downvoted swiftly, now they are not.
The downvoting here (as well as comment scoring) is probably my least liked thing about the site. It exacerbates the already prominent issue of hivemind and seems to actively lower the quality of discussion. People seem to mostly vote based on emotional reaction. On paper, a downvote just doubles the value of a vote. Meanwhile the graying of comments that never deserved to be downvoted to begin with is infuriating an…
On HN the main goal of upranking is if one comment is more interesting/informative than another (or as a group test to see how robust its argument is if the voter has no experience to judge directly). Downranking ime isn't meant to be the method used shift the order of comments but rather to discourage a post that doesn't fit the HN culture/guidelines. OTOH most popular gamified discussion systems don't discourage use of reactionary downvoting, which can creep into other posting cultures.
The problem the grandparent post raises is if signals that voting users would ordinarily use to shape the continued posting culture (eg: downranking comments that don't fit in tone/substance) aren't used like they were intended to be and if the guidelines discourage meta discussion then there isn't any other avenue to inform users what the desired culture should be in practice.
Certainly one can post non-meta comments showing what type of comments one would like (and thankfully for most strictly tech topics here it's still reasonable) but if the culture shifts enough among the silent voting users then the concern is this erodes the quality of discussion as the signals for what is wanted/not wanted get skewed.