https://en.wikipedia.org/wiki/Onavo#Facebook_Research this should provide some background; this is the software referenced in TFA. Facebook bought a massively popular VPN service specifically to monitor their users' web traffic and app usage.
If all the users data was going through the VPN, Facebook defacto knows what the user is doing on the web making that suggestion moot. It's the on device activity they want.
Yup, and they wanted to shove nation-state malware in to Onavo to do it, it sounds like!
All I see is two snakes (FB, NSO) are fighting on which one will eat the little white mouse (our privacy). I did the article because there is always some thing to learn even in the gutter.
Sure, have any opinion you want as long as you base it on facts, and respect others who don't agree with you.