I did notice and get the challenge ribbons <3 it made me paranoid if I could somehow play a deck full of unique primes and not-primes (lol)
as odd as it is I would have also been satisfied with a gallery at the very end of the game (unlocking at midgame might spoil the immune combo one?)! but also the endgame card "add to collection" made me think maybe it would allow you to more easily 'maindeck' a certain number or even gain an extra copy (totally not in the bounds of what it 'actually' does and it's fine) and it's just more narrow than it seems I suppose.
oh since this game got spread to people in my server M10 seemed like it was a bit of a pain - I managed to get it in a 'consistent' way that was pretty cool, but one that probably wouldn't work if the AI was a bit smarter, it would be cool to know if there was an intended strategy in mind for it