You could potentially use the hack the author explained with one of those possible black-sites in Africa to see who's deployed there. A little more research and you can find their home address in the states. Now, tell me an enterprising counter-intel or terrorist organization wouldn't want that info.
Op sec is the military's problem.
This op-ed makes the argument that it is difficult for users and even the companies offering services to fully understand the impact of their privacy choices:
https://www.nytimes.com/2018/01/30/opinion/strava-privacy.ht...
A sort of concrete scenario here would be the app asking the user before uploading an activity and whether the user wants the activity and segments to be visible on the public parts of the service. Strava probably doesn't want to introduce that friction into their product, but maybe that is a better balance than having a setting allowing users to opt out.
People make mistakes, do things by accident. If the conequences are this bad, we should question the standards which led us to them.
They basically pluck an interesting route from the hotmap (as per other people's recent discovery), pretend that they have also run/biked this route and Strava will show them names of others who run/biked the same way. That's clever, but that's not "advanced" by any means.
It's also not a deanonymization as there's really no option in Strava for public _anonymous_ sharing to begin with.