When we're talking about Facebook, we have a zillion concrete things to talk about, the services they provide, their open source and hardware, their refusal to play ball with Jobs' attempt to turn SV into a company town, etc. etc. All sorts of things one associates with successful companies, which here I define as actually doing stuff, ignoring the minor detail of making money off of it.
Theranos is not, and has never been a successful company, aside from hype and attracting investment. Their simple inability to properly and legally run a basic, conventional diagnostics lab suggests its not even in their DNA, even before one notes that they've only been able to get one finger stick test approved by the FDA.