The GNOME 3 stack does better than Windows at scaling UI elements based on text size; I'm successfully using a 1.4 or 1.5x scale on a 2560x1440 14" screen, and none of the UI elements look too small to me. Off the top of my head, I think the main elements that DPI-based font-size scaling doesn't scale are raster images (for which HiDPI allows supplying alternate high-res images similar to CSS) and cairo-based drawing elements (see cairo's "device-scale" support).