Local currency vs. the coin of the realm

How did the modern currency system develop? Ann Althouse of the University of Wisconsin Law School and Douglas Rushkoff, author of Life Inc., discuss the medieval origins of money in a short video from The New York Times.

According to Rushkoff, medieval rulers found themselves poorer than the merchants who were rolling in local currency, and were faced with the decision to institute "Coin of the Realm" in order to control currency values.

Coin of the realm a late invention?

Being a coin collector, history buff and a moneyer in the Northshield Moneyer's guild I was interested in listening to this. However, Mr. Rushkoff view of history is wrong. He talks about "local coinage" being superseded by a centralized "coin of the realm". He tries to make the case that late medieval kings invented "coin of the realm" to centralize the economies. He makes the reference to this happening just before the Black Death, so the early 14th century. He totally ignores the history of State coinage reaching back to the Greeks and Persians.

He uses England as an example but ignores the fact that they had a centralized coin minting system as early as Alfred the Great in the late 9th century. In fact Charlamange institued a centralized coinage that set the pattern for most of Europe from the 9th through the 14th century.

Even back in Roman times while some cities produced bronze coinage for local use, the silver coinage was centralized in the State.

My thought is this. If he is so wrong about basic historical facts, how can anything else be trusted? If you start with a wrong premise, say 2+2=5, then everything you build upon it is flawed no matter how logically sound.