> It’s less “the code for this is a mess”, and more “the code for this can’t be anything but a mess”.

Ok. But so what? As a customer that's not my problem, and Apple has a HUGE war chest to pay developers to maintain the mess. I have nothing but 1x displays externally and this makes Mojave a non-starter.

>Ok. But so what? As a customer that's not my problem,

It is. Customers pay for code debt too -- with bugs, slow performance, and slower moving features.

I really don't believe that subpixel rendering is such an inherently complex problem that there is no clean way to implement it.

From the OP it sounds more like its a pain to implement due to the number and design of abstraction layers in the modern macOS graphics stack.

The gp’s exposition is explicit but makes no sense to me, in a scenegraph architecture all that would be very straightforward for example.