I just checked, and at the recommended 250% scaling at 4k on a 16" monitor in Windows, I can see 0-3 messages on the screen at once in Slack, and just under 34 lines of code and 113 columns in VS Code at default zoom levels. If I do a vertical split in VS Code, I get 51 columns in each pane, which makes it basically useless. Icons and even things like the minimize button are like a full centimeter across.

I don't understand the point of a high resolution monitor that you scale up. Just to have extremely crisp lines? To me the whole point of a high resolution is that you can have more information on the screen because it remains legible when small.