you are misunderstanding crt tv's

crt tvs are nowhere near as sharp as lcd's - technology moved a long way in recent years.
this sharpness was never on tvs. its real resolution was around 320x240 pixels.
composite video also has low resolution -
masked by interlacing and other such things.
there are many technology hacks in tv.
only professional crts ever had more than 400 lines of horizontal resolution.

it has nothing to do with codecs.