It is true though, that 4K scaled to 1440p will not be as sharp as a standard retina display.
There's a clear difference between my 4K 27UD88 and my 5K iMac. But there's another clear difference between my 2010 iMac (1440p native) and my 27UD88, in favour of the LG.
In short, for 1440p:
5K retina > scaled 4K > native 1440p
There's a clear difference between my 4K 27UD88 and my 5K iMac. But there's another clear difference between my 2010 iMac (1440p native) and my 27UD88, in favour of the LG.
In short, for 1440p:
5K retina > scaled 4K > native 1440p