1) Rather than efficiently referencing a single sprite.svg, the svg source must be inefficiently inlined, page after page.
2) Rather than use SVG's animated transforms, the spinners must be animated using CSS instead. Don't forget the CSS dependencies or the sprites won't animate!
3) Everything is flat. Not because that's the style, but because webkit won't properly render gradients, drop shadows, inner shadows, etc.
https://bugs.webkit.org/show_bug.cgi?id=105904
But hey, at least webkit does kinda work with <use> that reference an external file. I just checked, and Chrome/blink doesn't work at all. It seems Firefox doesn't do animated transforms anymore. It did once. Opera (before it switched to blink rendering engine) was the only browser that worked nearly flawlessly with SVG.
SVG would be so great, if it actually worked. Why do we need ruby/node to do this? See above.