I always hate this mentality because the original anecdote relates to poetry, where the curtains can't be "just blue" because they didn't exist until the author told you about them. they could have been any color, or no specific color at all. the author made a choice to tell you about the color of the curtains, and part of understanding media is asking why they did.
i think the “sometimes the curtains are just blue” mindset has led to the downfall of media literacy