Is this suggesting that this would rely on browser implementation? ... Is this serious? What motivation do browser-creators have to implement this? Google wants the javascript widget so they can properly track everything, among other reasons. Who would back this? Who would develop this? This isn't like playing a media file, this is a highly interactive piece of content, with a metric shitload of complexity behind it.…
The difference is that you really can't do very well without . Handling encodings, using video hardware, being energy efficient...this is a lot of low-level graphics stuff. It's a primitive.
In contrast, you can make a map with JS and SVG/canvas/WebGL as good as a browser could do it.