One reason would be that LLM's don't tend to output verbatim pieces from their dataset (unless explicitly prompted to do so). This is made further complicated b

One reason would be that LLM's don't tend to output verbatim pieces from their dataset (unless explicitly prompted to do so). This is made further complicated by the "temperature" setting allowing users to make output even more "creative" than its dataset. In OpenAI's case, its writing style usually comes from OpenAI's in-house dataset they used for RLHF. This is what gives it the ability to chat and respond with its signature (perhaps overly formal and apologetic) tone. Although it can be used to write in other styles, sometimes it will refuse to because of this.