The WSJ misunderstands the three tenets of Theranos' dream, namely 1) 200+ blood tests 2) from a fingerstick, and 3) for under the reimbursement cost of regular tests. Basically, they were promising comprehensive, easy and low cost blood testing.
Finger-stick testing by itself won't provide enough value:
-Some analytes are susceptible to lysis resulting from milking the finger or are in too low concentrations.
-Cell counting and general chemistries require different anti-coagulants, so are multiple finger-sticks needed?
-Any volume of blood over say 50 microliters will require a trained technician to extract and the sample site will most likely need CLIA certification or the instrument will need a CLIA-waiver.
-The cost per test and throughput limitation of a novel finger-stick analyzer approach will lead to little additional revenue or foot-traffic.
-No killer application has been identified with the time sensitivity needed to justify the cost of installing a whole new system.
-Most people have more nerves in their fingers than in their forearms making finger-stick testing more painful. And the number of people that have a hard time producing large volumes from a finger-stick is WAY higher than that for a venous blood draw.
Theranos failed not because their minimally viable product was incorrect but because it was unachievable. The fraud was merely the manifestation of their deeply held delusion. Many still believe that there exists a more minimally viable product within reach. Best of luck.