Its text praising the divine virtues of the pharaoh Ptolemy V
Unfortunately, this article repeats this common half-truth. It neglects to mention the news that the text of the Rosetta Stone actually announces: general debt forgiveness.
If one reads past the Rosetta Stone's long-winded introduction about how royal and divine and legitimate Ptolemy V is, the text eventually gets to the point, which is an announcement of official acts:
under his reign [and as regards the sums which were due to the royal house] from the people of Egypt, and likewise those [which were due] from every one who was in his august service, His Majesty remitted them altogether, howsoever great they were...
It goes on in detail. Of course, this act is intended to consolidate political power, but why tell any history if that's all we can say about it? It's not common knowledge that general debt amnesties were a common feature of ancient economic life, and this kind of writing is perhaps why. Reducing an official act to "propaganda" is often just a way to dismiss governance that one disagrees with.