SVG has… weirdnesses. I couldn’t say exactly what they are. But it feels like an older format from an XML-centric era. It also feels fairy lax on “optional features” and ambiguous spec (although I’m not sure this is true). There are noticeable differences between different rendering engines.
Most of drawing works fine as markup. However, animations and simple state changes are awful. CSS is much easier to use for some of those purposes.
I’d very much forgive SVG for its clunkiness, after all it’s old yet very powerful today. It’s a prime candidate for a revamp.