-- yes, that pronouncement was quite a shocker! I'm glad they said "accidentals" rather than "sharpy flatty things." lolz
Their effort could improve -- perhaps
far enough to produce a net knowledge gain for some
readers -- in any of several simple ways.
Two trivially obvious examples...
Possibly interesting: "I analyzed the
chords KEY AND KEY CHANGES
of 1300 popular songs for patterns."
Possibly valuable: "I analyzed the chords of 1300 popular songs IN THE SAME KEY
Both could still be misleading to the novice -- and flaky from any educated standpoint -- but less harmful to the reader.