Fixing begins at "someone screwed up". Blaming delves into who screwed up, which is usually not required to fix the problem (since there may actually be no one to blame).
In the case of Theranos the problem of "what went wrong?" and "who fucked up?" are effectively the same - either the investors didn't do proper due diligence or the founders misled them. You can't fix the problem without knowing the cause. It doesn't really matter whether you couch it in terms of "what" or "who"; knowing one automatically informs you of the other.
If the investors didn't do their proper due diligence, then they can take steps to be more responsible in the future. If the founders misled them, then it becomes an economic and political issue of how to address and further prevent such problems.
Or just throw someone under the bus and keep repeating the same mistakes.