cool Yang Xue-fei....hehe....lol...
actually all of u all are not wrong....but can't say that u're absolutely correct....what that matters is good sound is able to be produce....like what ryuuga said...is the very likely sided to kotaro oshio,but tommy emmanuel doesn't use one finger to play melody oso...n can u say that his melody line is not good n not constant...is juz that different player got different preference of playing styles....

well...and also....4th,5th n 6th string not neccesarily for bass line only..it can be use for melody line also..for example....the beginning part of "Asturias",Tommy Emmanuel's Day Tripper,Merry Cristmas Mr.Lawrence by Kotaro Oshio....

lol....r u sure tommy emmanuel only uses picks to play arppeggios,he known as one of the best fingerstyle player in the world....

well,anyway, that's what u want to believe in...n it's fine with me....everyone has a different way of thinking....good luck