It wasn't the 7-page written interview questionnaire that was the problem, or the detailed follow-up phone interview before the real interview, which questioned you on your 7-page questionnaire to.. test you? Make sure you didn't plagiarize I guess? Okay, that's fine.
And it wasn't even the fact that they scheduled a full half day of interviews between multiple teams, so you're questioned for hours without a break. All of that, relatively tolerable. Most of them seemed really nice. It was a small team, so it was understandable they'd want to be selective.
What wasn't tolerable was the "final" interview with just the CEO and his assistant taking notes (who seemingly wasn't allowed to talk). All previous interviews had gone great, which he was also a part of, but now was his chance to really drill down and ask personal questions that should never be asked in any interview or professional setting.
After testing me again on my questionnaire - to which he said was so well written it made him skeptical - he started asking several in-depth questions, including where my values came from. Normal to talk about values, that's fine - but he didn't accept my answers and kept asking follow ups. Oh, your mother? Let's talk more about that. No, that answer isn't deep enough - go deeper. Oh, you're starting to cry? Don't care, keep going. Yes, I want to break you. Hm, yes, interesting.
Needless to say I didn't get the job. They went with an older man. Most likely because he didn't get teary eyed when forced to talk about *personal* trauma he should have never been forced to talk about in the first place.