Why did the reform of Pope Gregory VII in the West begin later than iconoclasm in the East?

Why did the reform of Pope Gregory VII in the West begin later than iconoclasm in the East? What conditions did not exist for its holding before?

For the success of the reform of Gregory VII, a new type of clergyman-official was needed. Before, there was nowhere to recruit such people, but by the 11th century, the revival of the cities of southern Europe began, and there were many professionally literate churchmen.