"even a 500mm (!) portrait was not only acceptable but ..."

Beyond about 180 - 200mm on 35, there is very little change of perspective ("compression").

If you double the standard focal length, there is a very noticeable difference. Doubling again, to 180 - 200, there is a less-but-still noticeable difference, and so on. One advantage of longer lenses is that the background fades into an abstract mush.

The point is to use what you like, what works for you and your subject.