> A decade ago, when I was a senior in high school, “Jimmy,” a jilted ex-patient of my dad’s, began stalking our family. Over a period of months, verbal harassment escalated to threats of violence and we soon found ourselves accompanied by police escorts for the better part of a week

> ....

> In Jimmy’s case, though, I simply cannot fathom how Instagram made this connection, despite quite a bit of legwork on my part to do so. He is not (and has never been) in my contacts, nor, after searching my email accounts, have I ever typed his name or even been forwarded an email about him. The more elaborate explanations I’ve entertained are nakedly conspiratorial, and so I’ve written Jimmy’s case off as a mystery that will remain unsolved, like a ship sunk in deepest waters.

The author described in sufficiently meticulous detail that Jimmy's location and presence felt through verbal harassment etc were frequently in close proximity to the author's entire family. I can think of at least a dozen clearly non-conspiratorial ways that Instagram has made the connection.

I think the author is living in the same bubble that much of the Internet is in: that the tech companies don't care to track us in the 'real world' and that most of it is still done with tracking pixels or smart-advertisements.

Instagram/Facebook openly use location and photographs to identify subjects and track them. This is no secret. If there is any remote possibility of a person having been anywhere near you for the last 10 years it should be assumed Instagram / Facebook already know about it. Any assumption less than that sounds conspiratorial to me ("don't worry nobody cares to watch you" etc).