What kind of MacBook do you have exactly? Year, size, graphics hardware and OS.

Reports I read stated that while you can select it with SwitchResX it was scaled.

I never tried installing it myself because I’m not a fan of modifying the system on a Mac, especially one I don’t own.

From my poking around I think the horizontal resolution is the problem. The system scans possible resolutions to see what works. Apple just never expected a single display that wide.

There’s some reports that newer MacBooks with discrete graphics on Catalina can indeed run this resolution. It used to not work regardless of hardware, now apparently discrete graphics MacBooks can run it. Maybe because they updated the drivers/system for their new super fancy monitors.

You probably have to update the monitor info DB on MacOS. See https://apple.stackexchange.com/a/233854

Text looks similar to Windows and Linux (both of which definitely run at native resolution).

macOS Mojave 10.14.6

MacBook Pro 15” 2019

Radeon Pro 555X

Intel UHD 630

Right, you have discrete graphics. I do not which is why I am stuck with the MacOS driver bug for Intel display hardware.

I’ve seen zero reports of anyone successfully running 5120x1440 using Intel graphics.

To clarify: I mean I have no idea why Mac OS doesn't let ME select that resolution while SwitchResX does.

Go to the Displays panel, switch to the "default for display" option, then switch back to "scaled" while holding down the option key. Do you see that resolution in the list of options?

I’m not sure what SwitchResX actually does. None of the accounts I have seen online are thorough enough to draw any conclusion.

As far as I can tell it is the same as Option-clicking on scaled in the display preferences.