The limiting factor isn't atoms, it's always been knowledge. Before we knew what coal was capable of, it was just a rock. Knowledge unlocks abundance with the limited resources we have.
The fact that such a limit obviously exists contradicts the notion of infinite growth, regardless of how large that limit appears. The power of exponentiation ensures that this limit is practically within reach.
If the premise of infinite growth is wrong, then we should be thinking of alternatives sooner rather than later. That was my takeaway from the article.
That said, we can indeed refine say our software to some extent. But it's important to keep in mind software has significant limitations as well, and complexity theory gives lower bounds on problems of practical relevance. We might get a few percent faster (in terms of number of operations) sorting algorithms (and merge sort), for instance, but no more, at least for random inputs.
I think less clear are say quality of life or new experiences afforded by new media, new novels, new games, new ways of seeing things. I think there is indeed significant improvement to be had, but also we probably shouldn't get carried away this is some kind of infinity: all things are limited when it comes to a life. I do think simply lifting everyone to a good condition (mostly emotional and basic needs) has a very surprising and large coefficient of gain.