Going beyond the eye limit is silly, Microsoft says.

As Microsoft readies its Surface Book 3 to ship later this month, you might be wondering: Why doesn’t it have a 4K display? The answer, according to Microsoft, is simple: You wouldn’t be able to tell the difference anyway.

In 2015, the display resolution of the Surface Book was revolutionary: 3,000×2000 pixels, arranged in what is now a familiar 3:2 ratio. (It’s still the same in the Surface Book 3, though the 15-inch version includes a 3240×2160 display.)
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https://www.pcworld.com/article/3543799/why-you-may-never-see-a-4k-microsoft-surface-display.html