I'm not sure it works that way. Just because you can't see pixels individually doesn't mean the overall picture quality won't appear better. I'm too lazy to do the math, but I'm guessing on a 25" screen, by his math, I wouldn't be able to see an individual 480p pixel, but I'd still take the Pepsi challenge between that and 720p.

And sure, a high contrast 720p screen might look better than a mediocre 1080p, but that's not a fair comparison. It doesn't mean that given equal quality, higher resolution isn't better.

The real reason not to buy a 4k TV is that content is non-existent and probably will be for a few more years at least.