The png is only 103 bytes though. Btw your svg can be decreased by changing viewBox to 0 0 1 1, and also by changing the path to a circle (implicitly positioned at 0, 0)
For a solid color block it doesn't really matter. For the rest of the map sure, Google Maps in normal mode (instead of classic as in the article) is vector rendering based.
While yes, you could use SVG today, for performance reasons (not obviously for water, but more complicated stuff like an actual city) raster files are both more efficient in terms of computation time and more consistent in rendering with the only disadvantage of file size tradeoffs. Not quite a concern for computers and dedicated navi systems (in fact Google Earth and the Google Maps apps for iOS and Android* uses vectors, probably not SVG though), but other embedded systems don't really have the luxury of including a proper 3D or even 2D-accelerated drawing (there's a basic chip for raster rendering and relatively fast path drawing but city maps usually contains many geometric paths that overwhelm the graphics processor).
* If you know Android Go (not Android Auto), the Maps there are raster due to hardware constraints.
<svg xmlns="dear user agent, if you happen to run into a problem resolving ambiguities with any of the following tags, please use the namespace for Scalable Vector Graphics and not, say, one of the zero other contexts that xml ninjas will no doubt create over the next two decades of what I can only surmise will be a glorious outpouring of richness and complexity. I mean, we went to the trouble of creating a dang URL for the thing, so it's the least you could do. That is, aside from doing nothing, in which case Hixie will probably write a parser to just handle it. Best wishes, W3C. P.S. Cannot wait to see all the Javascript-driven SVG content that users will upload to social media. Look out, animated gif-- your days are numbered!"><path d="animateYourSVGArcFlagsFTW" /></svg>