Not always true. When doing Hires interlace UI graphics for PS1 if you doubled up 1 pixel vertical lines, and avoided harsh contrasts, flicker can be massively reduced.
Of course later consoles filter the screen and don't need messing about with so much , but they still run in interlace, but are almost flicker free when compared to an amiga.
So altering your graphics can massively reduce flicker, and has a lot to do with graphics displayed, and software used.
also...When I can afford a 100Hz tv. i'll let you know!
