The first explanation is that Robert Johnson sold his soul to the devil who, in return, gave him the ability to play the blues like no one else.
The second explanation is that Robert Johnson was about to get married and become a father but his future wife died during child labor. This tragedy made him a better blues musician.
Is the second explanation obviously better than the first? Or do you find the second explanation just as mysterious as a causal mechanism for becoming a better musician as the second? After all, how is grief from personal loss supposed to make one a better musician?