This means that each pixel roughly corresponds to a single photoreceptor in the eye, i.e. the nerve cells in the retina that convert light into biological signals,” adds Andreas Dahlin, Professor at the Department of Chemistry and Chemical Engineering at Chalmers. “Humans cannot perceive a higher resolution than this.”

This is the paragraph literally right above the one you quoted. Do you understand what they mean by “perfect” now? They are saying you literally could not precive a differece in resolution from the image and real life.