What makes a great rock vocalist? Is it the length of his (her) hair? Is it the tightness of his (her) pants? Is it his (her) body features, flat stomach and great muscle tone? Is it his (her) facial features, his (her) eyes, lips, nose and smile? Is it the way he (she) poses and pouts during the instrumental solos? Is it the quality of his (her) musicianship and that of his (her) band members? Is it the power of his (her) vocals? Is it the sound equipment and recording equipment and the expertise of the technicians operating that equipment?
The answer to the above is yes to all of it to a point, but it is a very important point. Having all the above is usless, if you can not sing on pitch!!!