[jerzyt]

At one of the Big Four advisory firms we were only allowed one-on-one interviews. I was never able to get a satisfactory answer for this rule.

Now I wonder if it was designed to prevent this specific scenario.

[SpicyLemonZest]

They may have a different answer, but the explanation I've gotten for one-on-one interviews is that it prevents the "grilled by a panel" kind of feeling. (I wouldn't know since I've never been in a panel interview.)