Then you'd expect this article to appear on the FP every week, surely? It seems more likely to me that whenever people write about something out of the ordinary, it would not happen ordinarily - otherwise there wouldn't be anything to write about.
No you'd expect people to be complaining about it somewhere at some frequencly...and it hasn't been established that isn't the case. However, if you search for "Google newsletter suddenly spam folder", you can easily find lots posts that are superficially similar-looking, from various time periods.