Writing (and printing) enabled them to impose their culture. For example, Pizzaro had the benefit of a thousand years of military history to draw from, thanks to writing and books. The Inca did not. Writing & printing is a huge mind multiplier. It's hard to overestimate it.

(The Inca Empire was, of course, also an Empire formed by the Inca imposing their culture on other tribes.)

At the same time that Europe was conquering America, the Mughals were conquering India. But the Arabic script did not supplant Devanagari in India. Had the Islamic empires adopted the printing press as strongly as the Europeans did, one could very well imagine proto-Urdu texts flooding India, literacy in the Arabic script being a requirement for social advancement, and Devanagari being relegated to religious use.