There's a lot of one-off nonsense in here, but then there is also: > Another example is using a 4k screen ona a 13” laptop. Much better in terms of battery life and price to use a 2.5k screen. Humans can’t tell the difference. Why did they use a 4k? What? Citation for sure needed. That's ~330 ppi, which is about where Apple's "retina" marketing ends up, so even with that optimistic view on things, it's still "just en…
Only for the phones, which seems like a poor comparison point. Their current laptops are ~230ppi; they base the desired PPI on viewing distance as I understand it. So by Apples standards 330ppi is FAR too high for laptop viewing distances.
But Retina is more of a marketing term than anything. I want higher DPI displays. They're good independent of the marketing. And to say that a human can't tell when it's dependent on viewing distance even for average eyesight is clearly wrong.