I think you're missing the forest for the trees with this statement and it makes your comment seem a bit reductive. It's not so much a dismissal of writing on a particular product (iPad) as much as the article is about optimal writing by hand, the best materials, and some of the reasoning as to why.

While you may be convinced writing on a screen or tablet is objectively superior to doing things the "old way" there is literature on the topic indicating otherwise you might want to consider - that being said, everyone is different in their preferences and anatomy. I for one can't stand to write on a plastic/glass surface with a stylus, the ergonomics feel wrong and my retention for journaling is significantly worse.