The main point Saadia Gaon is making below is that the sole purpose of miracles is to make sure that G-d's message to man is authenticated. He brings in the fact that prophets are normal people to show that G-d insured that the world would know the source of the miracles, and not attribute them to anything else. I quoted from the following passage because I thought it would be an appropriate support on your last week’s article dealing with people performing miracles. (If prophets cannot perform miracles on their own, how much more so can this be applied to the rabbis of our times.) I didn't add in any of my own commentary, because I do not think there's much to be added.
"I say also, that it was for this reason that G-d made the prophets equal to all other human beings so far as death was concerned, lest men get the idea that just as these prophets were capable of living forever, in contradistinction to them, so were they also able to perform marvels in contradistinction to them. For this reason, too, G-d did not nourish them without food and drink, nor restrain them from marriage lest any doubt arise in regard to the significance of their miracles. For men might have thought that such nourishment [without food and drink] was natural with them and that, just as that was possible for them, so too was it possible for them to perform miracles.
Thus, also, did G-d not guarantee to the prophets perpetual health of body or great wealth or posterity or protection from the violence of the violent, whether that violence consist of flogging or insults or murder. For if he had done that, men might have ascribed this fact to some peculiarity in the constitution of the prophets wherein they deviated from the rules applying to all other men. They would have said that, just as the prophets necessarily deviated [form the character of the rest of humanity] in this respect, so too was it a foregone conclusion that they be able to do what we cannot.
I say, therefore - but of course G-d's wisdom is above aught that might be said - that G-d's purpose in letting the prophets remain in every respect like all other human beings, while singling them out from the totality of them by enabling them to do what was impossible to do for the whole of mankind, was to authenticate His sign and to confirm his message. I declare, moreover, that on this account, too, did G-d not allow the prophets to perform miracles at all times nor permit them always to know the secrets of the future, lest the uneducated masses think that they were possessed of some peculiarity which brought that about as a matter of course. He rather permitted them to perform these miracles at certain stated occasions and to obtain that knowledge at certain times, so that it might thereby become clear that all this was conferred upon them by the Creator and that it was not brought about by themselves. Praise be, then, unto the All-Wise, and sanctified be He!
Now what impelled me to note down these points here is the fact that I have seen people whose preconceived notions caused them to reject the assertions made above. One of them, for example, says: "I deny that the prophet dies like all other human beings." Another refuses to believe that he experiences hunger and thirst. Another rejects the idea that the prophet cohabits and begets offspring. Another denies that violence and injustice can have effect on him. Still another denies that anything in the world can be hidden from the prophet. However, I find all their allegations to be wrong, false, and unjust. On the contrary, it became certain to me that the wisdom manifested in what the Creator had done in the case of his messengers was of an order similar to that inherent in the rest of His works, as it is expressed in the statement of Scripture: "For the word of the Lord is upright; and all His work is done in faithfulness." (Ps. 33:4). Scripture likewise says: "But they know not the thoughts of the Lord, neither understand they His counsel." (Mic. 4:12).