This is context. It provides background on a common criticism of Handel’s da capo arias.

The musicologist does not make this claim. While the nature of the repetition allows it to speak to audiences regardless of language, the musicologist does not compare this ability to other music.

This is the main point of the musicologist’s reasoning. While many critics complain of the imbalance between the text and music in the arias, this criticism can be refuted. In other words, it is undeserved.

The musicologist does not claim the repetitions are unnecessary. The musicologist instead claims the repetitions serve a vital function.

The musicologist is only speaking to one specific criticism. She doesn’t address other criticisms.