Firstly, I think AI speedup is very weakly correlated to anyone's ability as a dev. All the devs in this study are very good. I think it has more to do with falling into failure modes, both in the LLM's ability and the human's workflow. I work with a ton of amazing pretraining devs, and I think people face many of the same problems.
We like to say that LLMs are tools, but treat them more like a magic bullet.
Literally any dev can attest to the satisfaction from finally debugging a thorny issue. LLMs are a big dopamine shortcut button that may one-shot your problem. Do you keep pressing the button that has a 1% chance of fixing everything? It's a lot more enjoyable than the grueling alternative, at least to me.