It's not that that's stressful, it's the potential possibility of failing the interview and perhaps not being offered the job that causes the stress.

Yes, but I know (or at least believe) that I'm technically competent. Therefore, the more technical questions I'm asked, the better I'm likely to do on the interview and therefore more likely to get the job.

And also, if they don't ask technical questions, they don't have a bozo filter and I'd risk having to work with bozos.

It helps, I suppose, that I enjoy explaining things to people.

I like to steer it to something I'm passionate about. I think (hope) it helps me come off as intelligent and passionate about the work. When I'm talking about something I really care about I forget to be nervous and after the fact I sometimes wonder if I came off as too enthusiastic.

As an example, I love Haskell's type system. I will almost always try to explain to interviewers how Haskell's type system would benefit this or that problem, and how it compares with the languages they are using. If the interviewer is any sort of good programmer, we can usually get into a good discussion on the trade offs of different language features.

Of course, maybe I would be getting even more offers if I didn't use this tactic.

I could see this going both ways. On one hand, you are clearly knowledgeable about some of the right stuff on deep level. On the other hand, do you come across as more pedantic than pragmatic? At the end of the day the business is hiring to create value and make money, not to have good academic debates.