It's all in Nintendo's lawyers head.
Piracy is one of the rare cases where you can be convicted on imaginary damages which aren't required to be proven.
Piracy is a bit special, nobody could ever prove that the damages exist and no research has successfully demonstrated that they even exist at all.
There is a huge difference between a genuine product and a counterfeit. There is no difference at all between the original data and copies of it, they are exactly the same. In fact, there is no such thing as an "original" piece of data, they are indistinguishable from one another. You can literally check the authenticity of data via cryptography. Doesn't matter if it came from an "official" source or some "counterfeit" website.
Their use of the word "counterfeiting" to describe copyright infringement is just like their constant attempts to equal it to "piracy". It's part of their propaganda. It's intended to give such "counterfeits" the connotation of being lower quality products.
Ironically, it's the corporations who peddle lower quality goods to paying customers while "pirates" get the high quality products. A 6 MB video game gets blown up into a 100 MB obfuscated mess due to SecuROM, then the "pirates" write an unpacker and release the small and optimized version without any DRM whatsoever. Streaming services send you shitty compressed video with artifacts everywhere, meanwhile "pirates" get uncensored blu-ray remuxes.
Sometimes there is a difference. Sometimes the copy is better than the original (in that the copy frequently has had anti-consumer garbage like DRM removed).