system
A chat on subreddit /r/pcmasterrace
human
Even 1080p on a 4k monitor would look blurry when using the monitor's built-in scaling functions despite having a perfect 1:2 ratio. Only something that can specifically do integer scaling like NIS can make a crisp pixelated 1080p on a 4k monitor.
gpt
Yeah I have a 1080 ti and a 4k screen FSR helps a bit but ideally I want stuff in native or it really doesn't look flash. 1440 p is a great compromise although I can easily see the difference on my friends monitor.

Another issue people don't think about is UI scaling as some games don't keep it in mind and it can get quite challenging to navigate and play. Worst offenders of UI are age of empires 2 2013 remaster and civilization 5.