I posted this in another thread but there are some applications where this display technology is actually needed. For example with VR/AR having a 1000Hz display would mean each frame is only displayed for 1ms. Being that quick would mean the headset would be able to better display the micro movements your head and body makes which inturn reduces the disconnect and motion sickness people get with VR/AR.
90hz is generally enough for most people to not get motion sick. Some headsets do 120 which is like 8ms frame time. Humans can barely detect a flash of light that lasts for that long.
The last sentence is simply incorrect. Humans can detect single photons in specific environments. https://www.nature.com/articles/ncomms12172
In real environments it depends very much on the brightness of the flash of light.