[scanlimes]

You are mistaken on two counts.

CRT TVs were designed around interlaced broadcast signals, but CRT monitors most certainly supported high resolution progressive scan video. The much vaunted Sony GDM-FW900, for instance, one of the last great CRTs before LCD monitors took over, supported progressive scan resolutions of 1920x1200 at 85hz.

And the NES and most early game consoles really did output a progressive scan signal that CRT TVs could display, through a hack known as "240p". Basically, the device only ever outputs odd fields in an out-of-spec NTSC signal, giving the effect of a progressive scan image with half of the vertical resolution. CRT TVs, being "dumb" analog devices, would just keep redrawing over the odd lines every time, and never ever touch the even lines.

This is the source of the "scanlines" effect of darkened horizontal lines spanning the screen, as these lines were never directly hit by the beam while a 240p game was running. It's also part of why these old games look like crap on modern LCD TVs, as almost all of them have scaling hardware that is ignorant of the 240p hack and incorrectly treats the signal as if it were interlaced, producing tremendously ugly results.