Lol, please describe a use case to me where you’d be watching Netflix IN A BROWSER, on a screen large enough that you could differentiate 4K.
I've got dual 27" 4k monitors hooked up to my PC. You can also hook them up to a Mac. Or hook a Mac or PC up via HDMI to a 4k TV. 27" iMacs are also 4k. AFAIK there is no Netflix app for OS X like there is for Windows so any viewing on a Mac would be in a browser.