I thought this was always true? What’s new about documentation being important?
If LLMs get more popular, fewer people will actually "browse the web" which could reduce the need for it to be published. At the least, fewer people will ask stack overflow questions for the LLM to learn from. So there could be an island of knowledge where LLMs excel at topics that had mass volume published before AI, and be much less useful for new tech developed after.
If your technology has competition that's already in the training data, the only way to make it equally accessible to LLM users is to ensure there is concise, available documentation that can be fed directly into those LLMs.
That's why "copy page" buttons are increasingly showing on manual pages eg. https://platform.claude.com/docs/en/get-started