My complete guess is there's a level of bravado or over-confidence about it.

It's obviously massively generalising, but I'd say someone without ADHD is more likely to feel like the number of tasks they can do at once is only limited by pesky things like physics and time, and LLMs "solve" this by allowing them to do more at once.

A bit like when a good manager takes on more and more reports and their ability to manage the larger team goes completely to shit, but without the useful feedback loop of the grumpy, mismanaged team.