I don't think the logic is sound. The psychological finding she's applying is that willpower is a finite cognitive resource. It isn't sound to apply that find

I don't think the logic is sound. The psychological finding she's applying is that willpower is a finite cognitive resource. It isn't sound to apply that finding to all decisions you make while using an app -- only the decisions that involve willpower. She generalizes to all cognitive resources being finite... If your UX asks the user to make choices, for example, even if those choices are both clear and useful, the act of deciding is a cognitive drain. And not just while they're deciding... even after we choose, an unconscious cognitive background thread is slowly consuming/leaking resources, "Was that the right choice?" ... which sounds plausible and may well be true, but is much more general than the result she's building on. I'm inclined to think she's right, though. It would be interesting to know if the psychological research has already been done. The willpower results are only well-publicized because people have a compelling personal interest in it.