The issue of scaling isn't so much about scaling in display dimensions but display pixel density. All the different resolution raster images stored in an ICO fi

The issue of scaling isn't so much about scaling in display dimensions but display pixel density. All the different resolution raster images stored in an ICO file were all displayed at the same ~96ppi of Windows. With high DPI displays and scaling a "pixel" is no longer necessarily a hardware pixel. Raster icons that display without upscaling on high DPI displays balloon in size quickly because they need 2x to 3x the number of pixels as the 1x version. Vector icons can have tiny file sizes but can be rasterized at any needed resolution and density. The hieroglyphic-style icons remain sharp and distinct at most resolutions and densities. You also need to keep in mind the icon sets you mentioned (Material etc) are meant to be used by third parties. They're sort of indistinct and non-offensive because they're supposed to work with a site's branding. The icons are not supposed to be a site's branding. Windows' icons were part of the Windows product branding.