ʿIṣmah refers to protection from sin; tawfīq to enabling obedience; and kashf al-ḍurr to removing hardship. People pray for these benefits and value them. They are not distributed identically to every person in every circumstance.
The counterargument to the optimum-benefit thesis is that, were every additional advantage obligatory, every possible instance of protection, ease, and good would have to be furnished. Yet a servant may pray for a gift without treating it as a debt that must be paid.
Therefore, the legitimacy of supplication is compatible with denying that every requested advantage is obligatory.