Well I mean not everyone; apparently there's a condition that causes people to not be able to visualize anything in their heads. There was a funny story on reddit about a woman who had her own condition that would cause her to associate....different things (?) with objects and had a vivid imagination, and her boyfriend who thought she was making it up that she could visualize stuff in her head, only to realize from all the people he talked to that he was alone in his inability to visualize stuff in his mind. Apparently it's some kind of rare condition.