It also helps editors later be more flexible with the format... if someone wants to reuse the insight you taped in a new medium (say, they want to put it in a documentary) they might want to have you saying the whole thing rather than to provide the context of "there is also an interviewer".

The Song Exploder podcast does this very well; each episode is recorded as an interview between the host and the artist, but because the artist is answering the questions with a restatement of the question, they can edit it so that it just sounds like the artist talking through their project (you almost never hear the host ask a question).