Comment by kprybol

Healthcare data can't be shared the way the browser histories, cell phone location data, etc. can. It's a completely different set of a rules that people have to play by (HIPPA for example). I build machine learning systems using healthcare claims and EHR data and without the direct cooperation of several large insurance companies (and access to their data) we'd be dead in the water. Even with access to their data there are incredibly strict limits to what we can and can't do with it. You can't just go out and collect healthcare data the way you can many other types of data.