I don't think he's "suggesting" anything. He's noting that two phenomena are resistant to story-telling.

This idea that there's an agenda for every observation seems to have started in the past 10 years. I find it very strange. It really shackles the mind, and conversation.

I notice my mind tends to think this way as well. Thinking about why I will think that usually yields recollections of people making "innocent" observations while they clearly had ulterior motives; such memories are in-person events, not this sort of interaction online. That said, it's easy to (read: difficult not to) apply similar heuristics to online interactions.

Not to excuse it; I agree with your conclusion. Hopefully such an understanding can help people to be patient with the behavior despite the annoyance.

Which would seem to argue in favor of what I understood to be the article's point, which is why I'm curious to know what he's pointing at.

The parent didn't make any suggestion that the models are wrong. "the math is simple" means that not only does the model work, it's also simple to calculate. That leaves the interpretation that seeking good narratives will sometimes be fruitless.