Rolling Stone is a magazine for rock and rollers. The list here reflects no more than the tastes of their readership. Of course you can't take it seriously. Even fans of the Rolling Stones (band) like me will be baffled why Keith Richard is on the list and Mick Taylor is not. However we try to measure the achievement of our favourite musicians, at the end of the day it all comes down to whether we like noise they make. Even in a field of music which I like, I can't say that one guitarist is better than another once they have reached a certain level of technique and musicality. I would rather hear Peter Green playing, "Man of the World", Eric Clapton playing, "Crossroads" and Mick Taylor playing, "Stray Cat Blues". None of them is the "best" guitarist. So how can we measure the achievement of Segovia against that of Bert Jansch or Charlie Christian?