Because most followers of justice believe that absence of grace is like absence of power and means, and that a duty with respect to someone, who is devoid of required grace is like a duty without power and means of accomplishment and presence of encumbrances, and that a person who deserves a grace and does not receive it, has legitimate excuse not to comply with Divine rulings, just as someone who is imprisoned and restricted has a legitimate excuse not to perform a task that cannot be performed while being incarcerated.