Whatever sort of music you sing, whatever quality of voice you have, you must adapt your technique to the medium that you will perform in, and you must do it in a way that won't harm your voice over time--that is what voice training is about. Nothing more or less.

The voice that is pleasing in the parlor may not carry in a noisy pub, the voice that can fill a hall unamplified generally has qualities that don't record well--and that's where it starts. What may seem like mumbo-jumbo is all intended help, not hinder the singer.