I actually don't think this article was LLM generated but these two sentences suck. I think they were moved from another part of the article without being modified.

First, "the hardest lesson". What lesson? It is out of context. Nobody was talking about lessons before this.

Second, "the bottleneck wasn't what we were measuring and observing". Of course the bottleneck itself wasn't that. They couldn't discover what the bottleneck was using the information in their measurements and observations.

It is a clunky and frankly incorrect passage in an otherwise well written article.