There's no doubt four color components can produce more colors, or if you like, shades of colors, than three. The problem for RGBY, from what I've gathered, is it's compatability with the current RGB standard. That standard is why a film video, or one from a camcorder, or a still from a digital camera displays with correct, natural colors on a TV. RGBY can go beyond the CIE Gamut triangle, but when applied to RGB based material displays incorrect colors, so it has to be curbed, defeating any benefit. Professional reviewers start by calibrating the set to the CIE Gamut and then of course say it has no advantage.
Then there is also the question of just how beneficial that color expansion, if the color standard were increased beyond RGB, would be to the viewing experience. Considering the tremendous cost, I seriously doubt I'll live to see the change.
No one here is JC, and ego trips should be left at the door!!!