Content has always been the primary focus of whatever setting and way it is to be used: novels are serial, broken only by chapters; non-fiction works are segmented by subject and accompanied by footnotes and references; work instructions are divided by processes, tasks and steps with references to parts, materials and commodities needed, and so on.
The content designer and creator always knew going in the role for the content being created. People --whatever their role -- have always been required to use the content as presented in order keep their job, succeed at their project or enjoy the story.
While it's true that some settings require content that can be used for multiple roles, this level of complexity is still confined to specific industries and settings.
With the rise of e-Commerce, everything has changed.