If anything this seems like a weak attempt to garner some attention for doublemap. I mean look at the link, its to github.io sure, but is there any actual code. No. Then why not link to doublemap's blog? Why create this false sense of open community (by linking to a github page) and sharing if you're not really sharing anything. You're basically detailing what you did in text, but in no way do you share your code.
The point here is that "Google" is no longer synonymous with "map" and that there is finally some choice in the space. This post by DoubleMap shows that going with an alternative at scale is more than possible.