>There is no evidence or argument for exponential growth
I think the growth you are thinking of, self improving AI, needs the AI to be as smart as a human developer/researcher to get going and we haven't got there yet. But we quite likely will at some point.
>>tim333+(OP)
and the article specifically mentions the fictional company (clearly designed to generalize the Google/OpenAI's of the world) are supposedly (according to the article) working on building that capability. First by augmenting human researchers, later by augmenting itself.