Why is the performance review meeting considered the "Achilles' heel of the entire process"?

What will be an ideal response?

Many managers are uncomfortable with providing performance feedback, particularly when performance is deficient; this discomfort may lead to anxiety and the avoidance of the appraisal interview. Because each component of the performance management process plays an important role, when any of these components is implemented poorly or not at all, then the entire performance management system suffers.