The first wave was not chat, it was completion. Instead of saying "suggest some names for an ice cream shop", the first wave was "Here are some great names for ice cream shops: 1. Nice Cream 2." Chat was a lot more intuitive and low effort than this.
Chat is also iterative. You can go back there and fix things that were misinterpreted. If the misinterpretation happens often, you can add on another instruction on top of that. I strongly disagree that they'd be fixed documents. Documents are a way to talk to yourself and get your rules right before you commit to them. But it costs almost nothing to do this with AI vs setting up brainstorming sessions with another human.
However, the rational models (o1, r1 and such) are good at iterating with themselves, and work better when you give them documents and have them figure out the best way to implement something.