Just not true. This again is where intuitive/rational/objective/measurement based talk diverges from something called "listening". A platter pad with the same durometer as vinyl (is there such a thing as "the vinyl"?) may sound best with one turntable/arm/cartridge combination while a copper, cf, or bare aluminum (as Harry Weisfeld advocated for years with his turntables) may sound best with others.
@fsonicsmith FWIW, when I first heard a proper platter pad designed around the points I previously mentioned, measurements didn’t come into it for many years- it was all about the listening as you say! To your point: every turntable we tried the mat on sounded better than every turntable that didn’t have the mat; it was making a bigger difference than the cartridge, arm or turntable itself! IMO its a real shame its not made any more! The designer (Warren Gehl of ARC who spent many years designing it) of the mat once told me that the hardness of the mat is a key factor. This suggests that one could make a reasonably good mat if it were simply pressed of vinyl and otherwise had materials embedded (as his mat did) that also provided damping properties.