Grainne Yeats (Irish harper and music historian, 1925-2013) is quoted as saying, "What you had, basically, were beautiful young girls singing sweet folk songs, playing little chords, and they weren't really playing the instrument."
Let's think about this. Are we really supposed to believe that over 20 years (1950's and 1960's) there was no variation in the students? Normally a studio would have some brilliant students, many ordinary students and a few slackers. Among the ordinary students there would still be quite a range in talent and willingness to practice.
In other words, in 20 years we would expect to see some sign of the bell curve.
Yet Ms. Yeats claims to know that not one student became accomplished. Even worse - not one could play a melody. And stranger yet, every one was beautiful. Wow!
In my opinion, this isn't musicology, it's just being catty.