Triple Triad is at least plausible in real life. With Tetra Master, there are those numbers and letters which are so complex that very few people in FFIX's world even know what they mean. Yet, they still somehow manage to play. That's simply not possible. Imagine playing poker without knowing the value of each card...

"Well, I've got some cards with faces and some with numbers... they're all the same suit and..."

*opponent's cards change colour*

"YES!"