I have very selective memory when it comes to reading, but from what I remember of the 1st Edition of Lifting Shadows, on SC,
1) The main songwriters were JP, JR and MP
2) JM spent much more time learning very difficult bass parts (what JP and MP wanted him to learn) than being a major contributor to songwriting
Based on what I have read, I agree with ReaP it's kind of baffling how anyone can say that Myung doesn't contribute almost nothing.
Or, maybe it's more accurate to say he contributes almost nothing compared to JP, JR and MP. Much less, at least.