Having played guitar for more than 20 years (and recently having time to be able to play 4 hours a day) I've only just now broken past speed barriers and learning how to truly play the instrument. I've read and download HUNDREDS of books, seen many teachers, jammed with many people, watched so many videos; and maybe 1 or 2 books have hinted at what it really takes to play the guitar. I could easily explain it now that I know to anyone and have them at super speed within a year. I've heard the same story from others in regards to DJing, piano, producing and anything else. Unless the person has some obvious physical abnormality that allows them to do some skill; most people in normal physical shape can do what we would deem AMAZING things with the right teacher. Sure.. Maybe they won't develop PERFECT PITCH; but most of the greats didn't have that either.