Pretty much all modern displays are too sharp for low-resolution bitmaps designed for a CRT. The whole modern "pixel art" where you see the art being made up of visible squares is not what you actually would have seen in the 8/16-bit console eras on a TV. Later arcade cabinets were much sharper, but still pixels were more like overlapping circles with Gaussian blur than they were squares.

The Wii is fine on OLED, the issue is with older consoles. Anything designed for TV's before 720p was a thing are where you will run into display disparities.