A performing artist's only job is to tell the story
Whether you are a singer, dancer, actor, or musician, your job is to take your audience away from the world they left outside the performance venue, and bring them into the world and story you are inhabiting. The opera singer needs the technique to master the ability to use their voice to navigate all the intricacies of the vocal line while taking the text and moving the drama/story with the thoughts, emotions and the brilliant music of the composer, bringing craft to the level of Art.
The beauty of opera is that it takes all these aspects and combines them into a single person's performance.