People who write prompts can have emotion. If someone is feeling really sad and they say to a computer "draw me a sad thing" and it draws something really sad and they break down crying, and then they show it to you and you also break down crying, that meets your goals, but it probably isn't what you meant.
The sad thing was produced by the machine, as its idea of something sad. It is not s result of this particular episode of sadness.
Put another way, “draw me something sad” is too vague; a million people can issue the same prompt, and what comes out does not correlate to any specifics of their own experience of sadness.
