If we ZIP both SVG and TVG, the difference is not that large anymore.
For most of people, wide support is more important than 20% smaller file size. That is why it is hard for WEBP to replace JPG.
For most of people, wide support is more important than 20% smaller file size. That is why it is hard for WEBP to replace JPG.
Like you said, support is what matters. SVG is notoriously difficult to implement and it took forever to be supported everywhere, which also contributed to the persistence of Flash. TVG is supposed to be easy to implement, which seems to be to be the advantage.
JPEG, by contrast, is a pretty simple format with only a few minor quirks.
But then you haven't implemented SVG. You can't say "we support SVG", and you lack a good way to communicate what users can expect from your implementation. It's much easier to communicate clearly when you can implement a whole standard rather than a haphazard subset of one.
Also, parsing overhead is such a tiny fraction of the overall effort (in either case) it doesn't really mean anything.