[jasoncrawford]

It's not always assumed to be exponential. It was assumed exponential by Paul Romer because long-term economic growth is pretty exponential. Much subsequent work has followed that model, but not all of it.

[pishpash]

But TFP is not output. Exponential output growth can come directly from exponential input growth, which would be a trivial obvervation.

[marcosdumay]

> long-term economic growth is pretty exponential

Yeah, that graph with the largest time scale on the article strongly disagrees.