It is always good to know how to work something. That means that you can do that one thing over and over again. If you know why something works, then you can use it, add it to something else and further what you previosly knew!
Just because a person knows no theory and plays great doesn't mean that there is no theory in their playing. It just means that they can make the connection without thinking about it. this takes a special ability and untold hours of practice/noodling with scales and modes. The greats have been doing this since early childhood. These aren't prodigies, they are artists who have "studied" this thing their whole lives!
No eclipse happened and suddenly they had great musical abilities. (That was a "Heroes" reference for those of you who are not superhero geeks)
