Also so much of management is personal. Upper management doesn’t have visibility into your day to day and needs to trust you’ll deliver by the deadlines they set for their bosses/customers. It’s hard to trust someone you don’t already know.
I recall interviewing someone who had just a terrible technical interview, but honestly seemed like a good fit. In the interview it came out he had worked for and with two people who I knew fairly well (and respected and trusted.) Two phone calls later, and based on their experiences with him, he was on to the next round.
Okay, maybe that's not a fair argument on my part because you're actually using the positive feedback that you got from the mutual acquiantances and they could have given negative feedback, but it's still the case that some candidates don't get that opportunity at all.
In this case it was a benefit both to me and to the candidate.
Does knowing people in a field give someone an advantage