Apple has since ~2012 missed two things - there are people who want computers without (attached) monitors for numerous reasons, and they want user modular Macs (like the cheese grater MacPro).
I agree with that completely - "missed" is the wrong word on my part - they simply decided otherwise. But they did not proceed with an iMac Pro only successor to the trashcan Mac Pro, and specifically said in they interview with Gruber, Panzarino, etc that the new Mac Pro would be "modular". Nor are they replacing the Mac Mini by the iPad (Pro or not) & low end iMac judging by the Cook email. And finally did not leave external monitors to third parties for good.Apple hasn't 'missed' anything. They have very specifically chosen not to cater to these markets for various, real to them, reasons. You can be disappointed in that but don't mistake it for ignorance on their part. It's entirely on purpose.
I think you mean 3 viable 5k, not 4k.I'm serious! If you want to pair it with an equally excellent monitor what are your choices in the price range of the delta between a Mac Mini and an iMac? There isn't much out there. 1440p sure but there's like 3 viable 4k monitors on sale all over $1k each. You can go cheaper and get 4k, but then you pick your poison:
No HDR
TN panels
Low refresh
Wrong ports