+1 for an Interview?

Genuinely curious about this. Just found out that some IIs allow the applicant to bring a guest. Honestly, first thing that came to mind when I heard this was 'helicopter parenting.' I can understand bringing guests to a graduation/white coat ceremony, but to an interview? Can someone enlighten me with the reasons why some schools allow for this option?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums