>They are supported on just about every device and platform
Except they aren't. I recently used a simple SVG in a background and Safari wasn't able to render it properly so after trying lots of different things I gave up and used different sizes of raster images instead.
SVGs also are mostly unsupported for og:image tags (dependents on the app/browser). I know it's supper specific and I am not even sure if open graph is standardized protocol or not, but it's used everywhere.
What was the SVG that didn't work? In Jon's example in the original post, the SVG he embeds there was one he wrote in around 2005. That's a pretty impressive run for it to render 20 years on...
Except they aren't. I recently used a simple SVG in a background and Safari wasn't able to render it properly so after trying lots of different things I gave up and used different sizes of raster images instead.