I understand what the difference is between the Web Mercator projection and Web Mercator Auxiliary Sphere (WMAS). I also understand that both Google and Esri have adopted this projection as their primary projection for their web-maps which is why we have specialized functions that not only re-project between all projections, but are specific functions for WM, such as webMercatorToGeographic. So ultimately I was wondering why we use the WMAS projection, and the reason it has become a standard in web mapping. Is it a purely a result of two spatial giants moving in that direction or was it just solely because of accuracy reasons?
Additional Links:
Mercator Projection
Answer
I'm pretty sure we have Google to thank. Take a look at the original EPSG code WKID for Web Mercator. What does 900913 look like? Helps if you're at least a little l33t.
When Google Maps blew up a few years ago (2005ish), everyone started copying Google. This included Virtual Earth/Bing, Mapquest, Yahoo Maps and eventually Esri. Everyone wanted/needed to be compatible with the most popular web mapping platform. It has been the standard ever since.
Edit: per mkennedy's comment, changed EPSG code to WKID
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