[Paul Gregory]"Current TV's all come with HDMI input with which to connect to a TV. An ever increasing number of TV's are now 4K. Are the reason nowadays still just as valid?"
Nothing has changed in the TV industry as far as color matching goes. If you buy 5 different HD or 4K TV's from 5 different manufacturers and put them side-by-side and feed them the same signal I will guarantee you that no two TV's will look the same. TV manufacturers pride themselves on the cleaver ways the employ to make blacker blacks and truer colors. No one cares if they actually represent the real image or not.
This is why you always want to color correct on a hardware calibrated broadcast monitor and not a TV.