A bad reference=No job offer

A bad reference from a previous employer was a deal killer. Proof: my very talented (on paper) job candidate had all the qualifications. His resume looked like the job description. After 2 very successful interviews, a hiring manager calls a contact that has worked with my applicant to “get the skinny” on said applicant. It was a bad reference. Sort of a “buy at your own risk” reference. My client decides to withdraw applicant from consideration.

Just like that.

The applicant will never know why he is no longer being considered (because the employer will never break the confidence of the reference.)

Is this fair?
Would it be much fairer if more than one reference is checked? That was my request.

No, not in this case. The deal for this job candidate is dead.