Pretty much exactly this-- advanced stuff only express-able in Bitmap format (such as photos, complex patterns, blending modes, etc) cannot be represented in SV

Pretty much exactly this-- advanced stuff only express-able in Bitmap format (such as photos, complex patterns, blending modes, etc) cannot be represented in SVG. That is, unless you use a Bitmap embedded in the SVG, but then what's the point? It's just simpler to use a bitmap format right now.