Redietz I share your view. I think DI is not attainable by the masses. I don't think you can take a course and become a DI. Over the years I've seen three and maybe four players who might have influence over the dice. (Respects to regnis because I've never seen him shoot.)
But do you need to be a DI to have an edge at craps? I don't think so. If you are a smart bettor you can improve your chances of winning. And if you can make sense out of the performance of the shooter you can also improve your chance of winning.
Ever see a dark side bettor clean up at a table of wild dice throwers?