Final answer:
The provided text excerpts do not contain information about a character named Ellie or her decision to join a band. More context or specific source material is needed to accurately answer the question.
Step-by-step explanation:
The question regarding what convinced Ellie to join the band, even though she didn't play an instrument, is not explicitly answered in the provided text excerpts. The text passages given appear to be taken from different contexts, and they primarily deal with themes of music, artistry, and personal reflection. However, they do not contain specific information about a character named Ellie or her decision to join a band.
To assist the student in their quest for information, it would be beneficial to have more context or a specific source from which the question is derived. If this is a question about a story, providing the title of the book or the context in which Ellie is debating joining the band might lead to a more substantive answer.