It's mainly because the raster images are going to be more accurate than @font-face as they'll display properly amongst all browsers and OSes just like a PDF wo

It's mainly because the raster images are going to be more accurate than @font-face as they'll display properly amongst all browsers and OSes just like a PDF would. edit: Also the most obvious reason (which I forgot to mention) is that they are type specimens and type specimens are (AFAIK) always done in raster images.