Tama being the reason why Kaido’s army will be destroy is a magnificent poetic justice.
Remember that this little girl suffer from poverty, starvation and could not drink water from a water source. She is so poor that eating Oshiruko for her birthday was the most beautiful day of her young life. She never knew the luxurious and rich Wano of before, only the dry husk, the empty shell, the country is right now.
Why? Because Kaido wanted weapons. He, with the help of Orochi, transformed Wano in an arid and barren land. He wanted an army and used the Smiles to create Gifters.
The Smile which have a 10% success rate were used to feed the poor as a cruel jest. « Your country is destroy, your loved ones are suffering, you starve and cannot feed your babies and the only thing you can do is to frenetically smile or laugh ». Because of the cruelty of two men.
Tama’s ability destroying Kaido’s army is Justice.