Question

why do we use methods of power sharing if it weakens the country as a whole?

Answer 1

In India no doubt federalism exists but our federal structure is known as "Quasi federal" ie. India has a federal arrangement but it leans towards a strong Center. Hence even if we have power sharing, more power is concentrated in the hands of the center and according to article 3, "the center has the right to alter the name, area, boundaries of the state by a simple majority". The center can also dissolve a state if required. So although we have a federal arrangement with power sharing feature, the center is privileged with more power, hence preventing the weakening of the country as a whole, an arrangement popularly known as "Quasi federal".