Earlier quoted context omitted.
Most younger persons might not care about this, but some are buying dedicated video hardware like the XRGB Framemeister to emulate the picture that you had back then on old CRT TV sets. (scanlines etc) I don't like the sharp and blocky video you see today on modern LCDs when using old consoles. I also don't like the video filters that some emulators use to make the games not look too pixelated. I just want it to look…
A Framemeister isn't just for the option of emulating scaliness, it's for being able to satisfyingly play old consoles on a HDTV period. The built in upscalers in these TVs aren't designed for consoles and will mangle the video output into garbage.
For some consoles that output different types of resolutions depending on the game you'll also need to change the settings on a per game basis.
So it's only something for enthusiasts.