Earlier quoted context omitted.
Because if you do art, you want to make something unique. Artists don't create exact replicas of the same object so often that a hundred of them are found over 1000 years later (which implies that there were probably many thousands of these).
This would suggest that the "cool S" that showed up in notebooks, on walls, etc. throughout my youth was a religious/ritual symbol. Same with stuffed squirrels and singing bass and "Bless This Mess" crochets and barn stars...
And going back to the original question, making those dodecahedrons would have required considerable expense, skills, and effort. That's not the kind of thing that can spread as a low-effort fad, and an artist who's going to spend that much time on something would be even less likely to make an exact replica rather than something original.