@bradenslen Sometimes I don't think it's even volume driven, and often I suspect it's based more on having been put on lists by spammers for their convenience.
You're definitely right about emergency flashers, and it's exactly the reason I wouldn't turn the comment functionality off. In fact there are specifically two or three people who use them on occasion and just for their interactions I'd put up with 10 times the amount of spam I'm getting because I value them that much.
It's not too dissimilar to some of the refback spam I get for a very small handful of worthwhile notifications I've seen on the open internet that I would have otherwise been blind to seeing.