There is no logic in that statement.
How would new designs hide the volume in existence?
Most of the recent changes where done because the North Koreans were making very, very good fakes of the previous incarnation. The newer versions have additional security measures to help detect fraudulent notes.
Also, the Federal Reserve doesn't 'print' every dollar they create. Not even a majority. Most of the paper FRNs are actually overseas.
Yeah, probably their economy and currency were backed by counterfeit U.S. currency...............