I think HiDPI is another reason - these were from the "96 DPI" era where pixels looked the same on every screen. You can draw all your pixel art at 2x (or 3x) and scale it down at load time, but it's not super easy. Also, some of the RAM usage of modern apps is the need for a full backing store for each window - in the "true" win32 days like Windows 95, XP, or Win7 in classic mode, you'd be drawing directly to the front buffer, with no extra RAM/VRAM usage per pixel. Of course it flickered and looked bad, but it was fast and cheap.