A design document is a technical report that outlines the implementation strategy of a system in the context of trade-offs and constraints.
Think of a design document like a proof in mathematics. The goal of a proof is to convince the reader that the theorem is true. The goal of a design document is to convince the reader the design is optimal given the situation.
The act of writing a design document helps to add rigor to what are otherwise vague intuitions. Writing reveals how sloppy your thinking was (and later, code will show how sloppy your writing was).
An individual will usually only be an expert in at most one thing, so the broad quasi-expertise offered by the LLM fundamentally allows them to do things they couldn't do before.
At least for the moment and in aggregate across society, they have been significantly more life altering for individuals than they have been for organizations.
The moment money can buy dramatically better ChatGPT, things change. Large organizations get to concentrate their vast resources to buy more intelligence. And within the category of “individual” too, the elite may once again split away from the rest of society. Their child will be tutored by GPT-8-pro-max-high, yours by GPT-6 mini.
It was supposed to be a top secret government megabrain project wielded by the generals, not ChatGPT appearing basically overnight and for free on a device already in everyone's pocket. Remember that William Gibson quote “The future is already here, it's just not evenly distributed”? Surprise – the future is already here, and it is shockingly distributed. Power to the people.