Nice article. Thanks. It is certainly something that a lot of us here are naturally interested in. But With respect, I don't think that your observations constitute a mechanism. Digital Apps that are deliberately feature-restricted do not hold the same attraction. I believe that there must be some further mechanism at play.
Perhaps as animals were are primed for the tactile, and everything else feels ghostly. I don't know. All I know is that no expand I can come to will convince my young students of the value of analogue.
The advantage is being clear from potential distractions. A lack of "features" providing a direct line of focus on what you're writing.
Apologies if that wasn't clear from the article!