Tantacrul, the project lead for both MuseScore and Audacity, is a professional UI/UX designer and has once conducted a significant first-time user testing for Dorico [1], so I'm pretty sure that he already knows what you are saying. Given his latest video about Audacity [2] though, I guess that Audacity has a very diverse user base and it might be hard to do the user testing while accounting for that diversity (the article you've linked specifically mention this issue).

[1] https://www.youtube.com/watch?v=S-3wEC6Fj_8

[2] https://www.youtube.com/watch?v=RMWNvwLiXIQ (includes an interview with original Audacity developers)