New high-end PCs indeed use high DPI displays, but color LCD monitors are now used in cars, dishwashers and microwaves. These are not high-DPI, and they often lack CPU and GPU power to handle high DPI.

Here's a library I've made for an embedded Linux device: https://github.com/Const-me/nanovg At 5" 800x480, subpixel AA improved text a lot.