Hello, article author here.
I wrote the article to notify an audience a little bit broader than Hacker News. There are many people who seem to think that it's only Google or Apple or Facebook they need to worry about; or that if they get GrapheneOS they are now really-secure and really-private (which they are, from Google, but not really overall). The very idea that their cellphone carrier may have their location, even without their phone cooperating, is often a foreign idea they never thought of.
This is, of course, a very long rabbit trail that never ends. Your license plate could get scanned. You could get picked up on cameras and run through facial recognition. But it's still important to call out areas that people may not have considered. Imagine a journalist - if nobody calls this out because "everyone knows," she might have installed GrapheneOS, signed up for ProtonMail, paid with cash for a SIM card, and gone off to cover some story without realizing this blind spot.
> I think everybody knows that if it's important not to be tracked by law enforcement (e.g. attending an illegal protest), you don't take your phone in the first place.
My home state would not have almost every police department armed to the teeth with IMSI Catchers if everybody just knew they weren't supposed to do that.