Josh Waxman has a sort of scientific answer that doesn't really fit the verse, but in my opinion his post makes a fundamental mistake. Namely, why is he presuming that the magicians created anything?
Here's the problem: The average first grader is taught that the magicians were able to duplicate the first two makkot. He was taught the court magicians knew real magic. And, unfortunately, the average Orthodox Jewish Adult never bothers to re-examine anything he was taught in first grade.(1)
But Josh Waxman isn't average.
He knows that verses about the magicians duplicating the makkot are ambiguous at best. (2) He knows that the view that the magicians had the power to create frogs, as recorded in Shmot Rabba, is a minority opinion. (3) And he knows that the Rambam insisted strongly that all magic is fraudulent (4)
So why is he pretending otherwise?
(1) Worse, the average Orthodox Jewish Adult gets upset when you tell him that his first grade understanding of parsha is superficial; he also angrily dismisses clear-cut rishonim, when you attempt to show him that Rashi's or the Midrash he was taught is disputed.
(2) The following interpolation demonstrates the ambiguity in the frog verse (translation of v. 7 is according to SRH):
6 And Aaron stretched out his hand over the waters of Egypt; and the frogs came up, and covered the land of Egypt.
7 And the magicians copied Aaron's with their magic charms, [nonetheless] frogs covered the land of Egypt. [Were the magicians hoping for MORE frogs? Or were they trying to undo Aaron's action? A clue that the magicians were trying to remove the frogs, and failed can be seen in the next verse when Pharoh calls for help. See next verse.]
8 Then Pharaoh called for Moses and Aaron, and said, Entreat the LORD, that he may take away the frogs from me, and from my people; and I will let the people go, that they may do sacrifice unto the LORD. [Does this sound like someone with much faith in magicians?]
(3) Rabbi Eliezer says the court magicians created frogs. The Sages, as recorded in Shemot Rabba, say that they could only gather the frogs in one place. They couldn't be created ex nilo.
(4) See note 1A