When Steve Jobs launched the iPhone 4, and with it the first Retina display, he described it as having a screen with so many pixels packed closely together that they were imperceptible to the human eye at a distance of twelve inches. He went to great lengths to explain that, because the iPhone 4’s screen packed in 300 pixels per inch, most people wouldn’t see them at all when the phone was a foot from their eyes.
My understanding is that there is a limit of what resolution the human eye can resolve.
https://en.wikipedia.org/wiki/Retina_Display
https://www.macworld.co.uk/feature/apple/what-retina-hd-display-are-they-worth-money-apple-3466732/