In a recent question about prestidigitation, one of the answers mentioned the idea that, when interpreting the effects of a spell, you should assume that a spell can never be used in a way which would make it equal or better than a spell of higher level; in that case using the Prestidigitation cantrip to accomplish something which seems to be more suited to the non-cantrip Purify Food and Drink.
The concept seems like common sense; if you could Purify food or drink simply through the "cleaning" function of Prestidigitation, then Purify has almost no value. On the other hand, the only official information I saw was that the 3.5e definition of Prestidigitation stated unambiguously that it could not duplicate any other spell effect.
TL;DR: Is there an official source that states spells should not be able to duplicate a higher level spell effect? Or is this just a common sense guideline to help determine the limits of spells with more vague descriptions?