Answer:
Because while the president of India is formally the head of state, and the commander of the armed forces, the president does not have any actual power, and his role is ceremonial.
Step-by-step explanation:
It is the prime minister of India who has real power, and who actually commands the armed forces, and governs the country.
This is why India has what is known as a parliamentary system: the head of government, who has executive power, is the prime minister, who comes from the party with the largest amount of seats in the parliament.
This system is inherited from Britain, where it was first developed. In fact, the president of India is the equivalent to the Queen of Britian. They are heads of state, but they do not hold any real power.