Based on my interviews, it became clear that the students’ goal was less about reducing overall effort than it was about reducing the maximum cognitive strain required to produce prose.

[...] the Brain-only group suggests that writing without assistance most likely induced greater internally driven processing…their brains likely engaged in more internal brainstorming and semantic retrieval.

There is indeed some concerns cited by the MIT paper: reduce students' ability to retain and recall information; bypass the process of synthesizing information from memory, promote a form of metacognitive laziness and avoid the intellectual effort.