"definitely an OP-is-autistic problem" is an absurd claim to make about an internet stranger, and violates comment guidelines https://news.ycombinator.com/newsguidelines.html.

I don't agree. While yes, it's definitely possible the interviewee handled it poorly, I have seen enough poorly conducted interviews to say it's just as likely the interviewer was the problem.

My best guess is that as a mental health startup geared toward expanding access to therapy services, they were fishing for candidates who had some kind of experience with the industry, or who could prove their fealty to the mission. For example: "After grieving the loss of my brother, I tried to obtain counseling services. But my private insurance didn't cover that, and when I looked for supplemental insurance, I was stuck in a byzantine maze of options. There was no centralized and easy way to see what might be covered, and for what cost; all of it was hidden behind sales reps you had to contact over the phone. That's when I came to understand the value of the kind of service ACMECORP is looking to introduce into the market."

From the details I read in the post you are almost certainly wrong, not to mention being reallying condescending.

The interviewer has control over the room. They steer the conversation. They could have stopped this at any point. Instead they encouraged OP to go deeper for 90 minutes.

That wasn't OP misunderstanding a question, that was an interviewer enjoying the power trip.

It might be cultural as well; I'm Polish and living in UK made me change my habits of answering "How are you?" questions. Same with Dutch from my experience - there are cultures where people say what's on their mind without the "I'm fine, how are you" bullshit.

To be fair though, drama-dumping goes beyond that