It formalized an informal practice that we've had for a really long time: don't just think about the subject matter; think also about, and in fact, primarily about, the job that your content is doing for the reader or the viewer.
Formaliza una práctica informal que hemos tenido mucho tiempo: no solo piensen en el tema; piensen, principalmente, en el efecto que ese contenido tiene en el lector o el espectador.