The interviewers want to prove how much more they know, as compared to the candidate. Or worse, they have one optimal solution in mind and anything else is a square peg / round hole.
Ageism is also a factor with some age cohorts preferring to hire within their age groups who play with their cohort's favorite tech-stacks.
A badly behaved interviewer - arrogant, rushed for time and treating the interview as a nuisance, egoistic - all of these make it harder for candidates to get a job.
Data point of one: I have faced the worst lot of interviewers in startups and Unicorns, and have had the best-behaved and reasonable folks in FAANG companies.