they certainly could. Games can do 16ms frames, while calculating full physics simulations.
It's just that text editors of the modern day are programmed by people who prefer to not write it that way - mainly because it's quite hard, and the modern OS doesn't usually fit well into this framework of rendering for multi-tasking. And it takes more effort too.
Much easier to rely on a UI framework which adds overhead. The expectation is that the user probably won't care, and prefer that the software be more feature rich.
It's just that text editors of the modern day are programmed by people who prefer to not write it that way - mainly because it's quite hard, and the modern OS doesn't usually fit well into this framework of rendering for multi-tasking. And it takes more effort too.
Much easier to rely on a UI framework which adds overhead. The expectation is that the user probably won't care, and prefer that the software be more feature rich.