I believe it is mentioned, but not on that particular page. See this one [1] > Anatomical differences in human hands > We were given hints about anatomical di

I believe it is mentioned, but not on that particular page. See this one [1] > Anatomical differences in human hands > We were given hints about anatomical differences in human hands very early on. The ergonomic marcostick prototypes we created did not work on a few individuals in our test group. We noted that one person in particular could not make the thumb pose required for Standard Grip. Forced adoption of Standard Grip for this user led to chopstick cramps. We created the model T training marcosticks and model H finger helpers in response, but did not think much further about this thumb condition. > It wasn’t until after folks sent us more pictures and videos of their alternative grips, that we started to appreciate this as a prevalent issue. [1] https://marcosticks.org/the-art-and-science-of-chopsticking/ https://marcosticks.org/the-art-and-science-of-chopsticking/