Just because many chain retailers don’t accept them does not make them unusable. They still are used for many large cash payments, and they have to be accepted for paying a dept (like at a restaurant).
"Single pixel" is an interesting way of putting it.
That comment made me imagine a bunch of people sitting in a movie theater, watching a film that consists of nothing but a giant square that keeps changing colors and brightness, with the soundtrack from another film. The film is called "Blindness Simulator."
dd does not stand for "disk duplicator". That's a modern backronymization that doesn't reflect the original general usage of the command which is to "convert and copy". Efficiently (with respect to I/O) copying raw data is only one of its intended purposes; it also converts text encodings.
No, it does not make any technical sense whatsoever why an LLM of all things would make that connection.