The fact that you think it was suggested _by_ them is I think where your mental model is misleading you.
LLMs can be thought of metaphorically as a process of decompression, if you can give it a compressed form for your scenario 1 it'll go great - you're actually doing a lot of mental work to arrive at that 'compressed' request, checking technical feasibility, thinking about interactions, hinting at solutions.
If you feed it back it's own suggestion it's no so guaranteed to work.
It seems to be the "conversation" part, not necessarily "communication", one of the early stages in children's language acquisition is teaching the flow of back and forth responses and pausing for the other to speak: which seems to be what they're indicating in this article.