Oh god. I’ve met some seriously incompetent people when interviewing - to the point where I’m glad they are the one conducting the interview cause I never want to work with them. I’ve actually finished an interview where I was the candidate with “thank you, but I don’t think this is going to work out”.
To be clear, my point is more that lots of people who are competent at their core jobs and would be perfectly fine coworkers suck at interviewing (but are pressed into service doing it anyway).