Those requests were granted exactly as they had been made—sometimes in a way that yields certainty, at other times in a way that produces a strong presumption—that the supplication was the very cause. This is something well attested by people of sound intellect and clear insight, those who understand the kinds of evidence, the conditions that govern them, and their consistent application.
By contrast, belief in the efficacy of forbidden supplications is found mainly among the ignorant, who cannot distinguish proof from non-proof and who do not grasp the requirements of consistent evidence. It is typically found among the people of darkness—disbelievers, hypocrites, or major sinners whose hearts have been darkened by sin so that they can no longer tell truth from falsehood.
To sum up: knowing that something was the cause, or part of the cause, or a necessary condition for a given occurrence is often established with certainty, often with firm conjecture, and often merely imagined with no sound basis other than weak intellect.
It should suffice you to know that anything the Sacred Law has prohibited—whether it be a supplication or something else—that is thought to bring about the desired goal must fall into one of two categories: either it is not a genuine cause at all, like calling upon one who neither hears nor sees and cannot benefit you in any way; or its harm outweighs its benefit.
As for whatever is a genuine cause whose benefit exceeds its harm, the Law never forbids it under any circumstance. And every act of worship that has not been legislated, even though the motive for performing it is present and no impediment exists, is