1. Users have plenty of individual characteristics. If even ordinarily capable user’s can’t deduce what button does what, forget people with disbilities. It’s obvious you need to usability test this stuff. Gnome has neglected their basic duties.

https://www.nngroup.com/articles/usability-testing-101/

2. Human-Computer Interaction is a scientific field within Computer Science, and this is stuff from any 101 course. Do we really need to cite belief in gravity each time just because self-appointed ”developers” haven’t done the work of learning the basics?

Start here: https://www.nngroup.com/articles/ten-usability-heuristics/