I'm not aware of anyone ever really using print runs to generate the rarity numbers here or elsewhere. After all, on older games, how would you ever know how many copies of any given game still survive? Even newer games that don't sell well could have had significant numbers of copies destroyed to clear stock. My understanding is that the rarity in the DP guide is all based on opinion and the experience of the collectors who helped create that particular section. It's not just pulling numbers out of a hat, but it's also not objective in any meaningful way.