I'd be interested in seeing an example of a well-composed 9:16 portrait photo. All the ones I have found look awkward.

Yeah, portrait photos aren't as narrow as that. I just measured some of mine, and they're 5x7, 8x10, and 11x16. By comparison, 9x16 feels claustrophobic.

I suspect that a still image is also different from video because, without motion, there's no feeling that if the person might move a few inches to one side and go out of frame.