Bit's got it about right. Many of the greatest players of all time are not that well known. And many who populate the lists above are very good at what they do...but not nearly the avatar of their instrument. Have you heard of Lenny Breau? Chuck Loeb? Chris Theile? Jimmy Herring? Oteil Burbridge? Art Tatum? Just to name a few off the top of my head. I've got nothing against most all of the folks listed above but the list should pretty long, really, before you get to folks like Jon Anderson, Jack Bruce or Ian Anderson. V-e-r-y long indeed.