As a hiring manager, you know who you think would be a great fit. I'm always looking at how a particular individual fits into the rest of my team. And while I often find that there might be a few folks whose opinion I'd like to get on the candidate, there are also many cases in which that person just needs to check the box. Especially in large companies, you have to get certain people to interview them and get their feedback, but it’s probably not going to shift your decision one way or the other. It's just one more cog in the process that slows everything down. And by that point you've lost those individuals you were trying to bring on. It's almost like you're going back to the well to try again. It's so inefficient.
Years ago I read about how Google hires, and one of the key takeaways was that companies make a huge mistake by conducting an excessive amount of interviews. The data shows that there’s no point to do any more than five interviews because you should be able to determine whether or not you have the right individual by having the right set of people speak to them.