I would say that the mechanism for this is actually due to the nature of working with LLMs: they free your attention.

Say you're working on a project, and it does an ok job like what the GP says. Each step looks fine, but put together it looks off. You give it some instructions, and then you let it work.

But what are you doing in the freed up time? You context switch into another project and give that some instructions.

Now you have two or three or ten projects that superficially look fine, but you yourself have context switched so much you don't have the overview anymore of why exactly each project needs fixing.