That's fine, but there are many tasks (for example, natural-language processing) where there is no classical way to precisely define the steps you want to be pe

That's fine, but there are many tasks (for example, natural-language processing) where there is no classical way to precisely define the steps you want to be performed, and hand-tuning a list of keywords or heuristics is time-consuming and less accurate than reading through the texts yourself. In this case, providing high-level instructions to an LLM to read through the text and attempt to apply the spirit of your instructions is invaluable.