Win32 has a little less churn than AppKit used to. If you support the API surface of winxp from 25 years ago you can run a lot of stuff. Most teams inside Windows at MSFT also try to leave older APIs alone and introduce stuff in an additive fashion. Apple, by contrast, historically has app compatibility as a non-goal.

I said "used to" because anecdotally, I had a personal project I haven't released anywhere target AppKit, I haven't been maintaining it because life is busy, I recently rebuilt it for the first time in a long time and I was shocked that everything worked. ~8 years ago, you would need to do some porting to a new major release once per year. I skipped that maintenance for many releases and didn't need to change a single line. This tells me that desktop apps are not at all an area of major focus for them lately. Maybe swiftui is getting all the attention. They are doing something more resembling Microsoft, leaving the old shit alone.