Well, there aren’t any studies showing AI agents boost productivity, so it’s all we’ve got. It seems like a well-conducted study, so I’m inclined to trust its conclusions.
One of the articles linked from the OP includes links to such studies: https://theconversation.com/does-ai-actually-boost-productiv... - scroll down to the "AI and individual productivity" section, there are two papers there on the "increases productivity" side followed by two others that didn't.