You’ve hit the nail on the head.

I characterise llm’s as being black boxes that are filled with a dense pool of digital resources - that with the correct prompt you can draw out a mix of resources to produce an output.

But if the mix of resources you need isn’t there - it won’t work. This isn’t limited to just text. This also applies with video models - llms work better for prompts in which you are trying to get material that is widely available on the internet.