Depending on where you live you likely have a legal right to the interviewer's written feedback. I've never tried it (US) but I've heard of many other people (US) that were successful but you probably need to know w/e relevant law it is as I assume by default you won't get it.

That's a sure fire way to get blacklist from a company. No US company likes to deal with high maintenance candidates/ employees. The risk is too high to just move on and let it go. The best course of action is usually to come back in 6 months to a year and interview with another team.

I think respecting a red flag of any member of a team to stop a hire is a good practice.

I have encountered my fair share of bad interviewers. You don't even need to take my word, go on Blind and read all the horror stories from both the interviewer and interviewee.

I think the statement to be too generalized and doesn't address the power dynamics of the interview process. You assume they are good judges of character from a 60 minute interview.

all interviewers are subjective - it's part and parcel of the process...which is why you need to excise the trivia questions from the process