How are you defining "civilization?" Going by most, now antiquated, classificatory definitions, writing was a requirement to be a civilization, so your observation would be redundant.

But this does help us point out the flaws of the whole "what is/isn't a civ" issue. There were plenty of societies across the world for thousands of years that displayed so many of the traits of "proper" civilizations (e.g. urbanization, social stratification, centralized government) but did not use writing. The claim that it's essential to being a civilization beyond archaic definition semantics is unsubstantiated.