Google bought the technology so instead of using other people's technology it makes sense they would want to make their investment go as far as possible, if for no other reason than to be a big bully and push people around just like MS does.
For instance, the whole world used Apache and LAMP but MS had to shove IIS and ASP down our throats just because they could. We already had Flash but here comes Silverlight whether you like it or not.
MS had an advantage since they had their own OS and browser which was the dominant OS and browser they could instantly make anything they added a 'standard' regardless of whether any other browser on the planet adopted the technology or not. The more proprietary stuff MS could stick on the web, the more tightly customers would get tied to MS for all their needs.
Apple does the same thing with Safari and Quicktime, and all the other Mac formats and iCrud, etc.
Google obviously wants to be in that same situation and since has created Chrome which has finally gotten significant market share. While Google may not own the OS, which they attempted and failed with Chromebook, they have several wildly popular dominant web services which in combination of Chrome can easily be used to create their own proprietary web stuff.
Get use to it because Firefox and Opera are about the only two independent mainstream browsers left and neither have enough clout to do what Firefox is doing, which is to tell Google, Apple or Microsoft they won't support something because the simple matter is it will inevitably cost those browser only vendors market share which they're lucky to keep at this point.
If it wasn't for the vast library of Firefox add-ons I think it would've been a footnote long ago so they should tread lightly.