So you are saying that the pie is not grown by paying more, it's just that the workers are getting a bigger slice. Could be. That didn't seem to be the main point of the article, but that could also be true. I haven't looked at the data carefully.
The pie did grow, so it’s a benefit to society. It just didn’t grow enough that giving the employees a larger slice didn’t slightly shrink the owner’s pie. However, The owners pie shrunk less than it would have had the pie not grown due to increased efficiency.
I wonder how these studies captures the way the workers have more money that immediately flows back into the economy, benefiting everyone.
I think you left out the part about, "and at what point that creates inflationary pressure."
Is wage the only cause of inflation we care about? Guess so.
On the other hand, if people were going into debt with high interest credit cards, then it's very possible that demand doesn't actually change. Instead credit card debt gets paid off, or surplus income is banked as savings.