All through the 2000s Apple developed non-integer scaling support in various versions of MacOS X under the banner of “resolution independence” - the idea was to use vectors where possible rather than bitmaps so OS UI would look good at any resolution, including non-integer scaling factors.

Some indie Mac developers even started implementing support for it in anticipation of it being officially enabled. The code was present in 10.4 through 10.6 and possibly later, although not enabled by default. Apple gave up on the idea sadly and integer scaling is where we are.

Here’s a developer blog from 2006 playing with it:

> https://redsweater.com/blog/223/resolution-independent-fever

There was even documentation for getting ready to support resolution independence on Apple’s developer portal at one stage, but I sadly can’t find it today.

Here’s a news post from all the way back in 2004 discussing the in development feature in Mac OS tiger:

> https://forums.appleinsider.com/discussion/45544/mac-os-x-ti...

Lots of of folks (myself included!) in the Mac software world were really excited for it back then. It would have permitted you to scale the UI to totally arbitrary sizes while maintaining sharpness etc.