It's a know technique, I wouldn't say that makes it "valid". It also seems to be a inspirational technique i.e. adding an artificial limit to spur creativity.

The text is ultimately managed by a real human being otherwise capable of writing original text. That human being hasn't been exposed to English entirely through the corpus of test given, as would be the case of GPT, which has no previous knowledge of language.

TLDR; the technique gives the text to an already create human being, rather than expecting creativity to arise from the technique itself.