I'd love for more research to be made into PWM sensitivity, if only to find out roughly how many people experience problems with it.
I've never had issues with it other than when trying to film certain old displays, but then again, I've never had issues with PAL TV sets running at 50 hz interlaced, nor even old PC CRTs running at 60, which definitely was not 'flicker-free', so I'm probably on the far end of the spectrum compared to the PWM sensitive.
It's an easy thing to forget, as with many accessibility features. And it's going to suck to have the nominally best display be one you just can't use if want to not feel like gouging your eyes out.
I notice PWM all around me all the time. Lots of cheaper LED lights use it, and I see it whenever I move my eyes, also when not consciously looking for it - instead of a blur I see series of lamps as a brief afterimage.
As a child I got headaches from CRT monitors at 60hz and I could see them flicker. I haven't noticed the PWM on modern monitors, but maybe these Apple ones would trigger me?
I do have issues with PWM everywhere myself while CRT was not big issue. I did tinker with refresh rates though. And I think difference is that
1. CRT display phosphors had afterglow.
2. the cathode ray was a dot moving across the screen, that might be easier on eyes than whole OLED screen flashing at once.