Fonts have one great benefit, they scale very well, no matter what resolution we are running at the icons from fonts will look crisp. Images on the other hand are well known to be shit for scaling, hence everyone having to ship 50 versions of their icons/logos at different resolutions.
13:15
You could I guess ship one icon at very high resolution, but it's both wasteful AND there is no "best" algorithm for downscaling
The only small issue is that you either need high performance vector rendering in shader (slug is pretty good) or you need to render it out into a texture(edited)