For an an organization member, deniability is a way to contradict accusation from its organization about a misbehavior .
I call it the exit gate, because that's a way for someone to flee responsability.
Deniability increase in value for a member is detached from its organization.
And this happen when the organization treat him like a number, that typically happen when a company wants to scale for growth while keeping centralized and hierarchical management power.
Henry Mindzberg call such organization a machine bureaucraty.
Such organization can stay like this, like our own governments, or evolve into several decentralized and semi autonomous team called Adhocracy.
You can see deniability in action everytime a crisis happens in an organization, and it is nobody fault.
Certification, Diploma, curriculum and any credentials you can get are common tool to use deniability at your advantage. And, as I said, the power of these tools are as powerful as deniability is strong, or as powerful as the company behaves like a machine bureaucraty.
For a student, a Diploma can justify that his failure to find a job is diploma's fault, not his.
For a head hunter, a certification or diploma can justify to its boss that even if the new recruit was dumb, he had everything on paper, and thus it's not the head hunter's fault. The head hunter can then turn his head to the HRD.
The HRD will respond that this rule were made to scale human resource need at lower cost, and will turn its head to upper management. So on and so on.
The real underliying problem is that everybody is concerned about saving its own ass over the organization's ass.
To prevent such event, the organization has to change so the member can identify and attach them to it. If you don't get a job, you will not deny your fault and reject it on your family, because you identify with this organization (within Henry Mindzberg framework, your family is an organization).
One solution is to move to an Adhocracy, by keepings teams small and relatively autonomous. A small community is easier to take part in.
Other solution is to read Delivering Happiness
which is Zappo's CEO biography that explain his own solution to this problem. He call the solution the Culture.