I think one of the most compelling reasons to have a group or team interview is because it reduces a decision getting made about a candidate based on personal biases. I was shocked to learn from Adam Grant that a person makes a decision within the first 90 seconds of meeting someone, and that it's based on how people look (straight teeth, tall, balding man with shaved head etc.) That means people are making a decision based on symmetry and prejudices rather than actual aptitude for the job.