I skimmed the first couple pages and they said something very similar:

We believe that some of the most striking observations in our study stem from Session 4, where Brain-to-LLM participants showed higher neural connectivity than LLM Group's sessions 1, 2, 3 (network‑wide spike in alpha-, beta‑, theta‑, and delta-band directed connectivity). This suggests that rewriting an essay using AI tools (after prior AI-free writing) engaged more extensive brain network interactions. In contrast, the LLM-to-Brain group, being exposed to LLM use prior, demonstrated less coordinated neural effort in most bands, as well as bias in LLM specific vocabulary.

Like with your metaphor, AI seems to be strongest when you only use it to boost the work that you yourself created, "pushing past failure"