Mahagurus base their judgement keeping public taste and popularity of the singer in mind. In the end public can make or break a singer. Regardless of how good singer one is, if you are not original and cannot sell the music..it is no good and means nothing.
Originality is most important in making a singer famous and for his or her records to sell. Many singers on SRGMPA are very good but they are not better or different than the orignal singer who sung the song. The singer should be different and orignal to stand out and make his or her mark.