It’s said the core of every composition are the lyrics. It’s them to appeal to the listener and to make them relate to the story told. And the one who’s telling the story, who’s puting all his heart and soul into painting a vivid and haunting picture with the words spoken, better said sung, is the vocalist. He is the band’s front man for a reason - most likely he’s the one who has composed and ellaborated the lyrics therefore the song’s message and deeper meaning, he’s the one to reach out to the listener’s heart with the words his inspired and receptive mind, lastly his very own heart have originated.
The instrumental parts on the other hand breathe life into a song, let the listener find melodies to linger on his mind, melodies to move along to as the lyrics move him inside. The sound of the instruments back the vocals, strengthen, stress and amplify them - at times they even outshine the vocals. The moments they do, it shows each and every band member has his value, the right to be in the band as he contributes to the music created, as he helps to let the sounds evolve and unfold.