I loathe BNBR for its vagueness and subjectivity. I appreciate BNBR for its encouraging a culture of civility.
BNBR can be used to prosecute nerd rage (as OP explains it: aggressive snarkiness), since such snark is Not Nice. After all, BNBR is used to prosecute banter, which is meta-Nice, because moderators think it will discourage civility.
OTOH, there are plenty of snarksters here, particularly high-profile users castigating vices; and I don’t see snark being systematically nipped in the bud here before it escalates into outright BNBR violations. (I’m not sure I would either.)
You pose an interesting question: is BNBR the only thing that averts feral snark? No. The culture of the site ultimately is what averts misbehaviour. And since OP was curious about practice in other fora: if the fora are small enough to have an organic culture, that culture can self-moderate pretty well. In bigger fora like Quora, you need to build the culture by policing it. BNBR has done that here, but BNBR would be nowhere unless a critical mass of users bought into it, and policed it themselves, through reporting and downvoting.
That’s misbehaviour in general; trolling, for example, is here but is much less prominent than elsewhere. But feral snark? Much more borderline, much harder to extirpate, and much harder to get community buy-in that it must be stamped out than for trolling. And I just don’t see it is being prosecuted as aggressively. (And I’d rather it not be, precisely because it’s much harder to.)