I understand that. But in the grand scheme of things, the era of AF flim cameras was pretty short. And I remember the eye following focus when it came out. My initial reaction was "Wow, that's cool." Tried using a camera w/ it, and didn't like it. I think the reason that you don't see it on modern DLSR's, is because it's a technology nobody wanted. Focus and re-compose gives much more consistent results.
To me, I thought one of the biggest advances (after interchangeable lenses) in film cameras was TTL metering. After that, it was the program modes in my AE-1P. Never spent much time w/ an AF film camera.
Focus and re-compose doesn't work at large apertures even for static objects.