Have you ever read or attempted to implement a portion of the SVG specification?

It's absurdly complex, and there is little guarantee that the SVG spec is implemented completely and identically in different environments. I know of several native GUI SDKs that do not support a large portion of the spec.

Even something that should be easy like doing a wireframe or mockup in Sketch, exporting to SVG, then displaying that exported SVG in a browser on the same machine can display jarring errors in the rendered image.

And most of the cool shit in SVG - like embedded JS and the filters spec - are where those issues rear their heads.

What I'm saying is that SVG is as much a shitshow as HTML. It's just HTML with additional drawing semantics anyway.