Fire has 15 cards including pillar and pendulum. 4 other elements also have 15 cards. It's the most common amount.
The average, however, is at 15,916. The second most common amount is 16, and some elements offset it a lot, like Death with 18 and Entropy and Water with 17.
Of course, Sno made a joke, but if there's a reason Sanc is being introduced, I'd guess it's because denial decks work on all types of decks.