Because Facebook and Google are well known for not making arbitrary
changes to public apis and configurations.
More importantly as an Open Source project hitching our code to the configuration of a
third party proprietary system is terrifyingly bad karma. Push is an exception ONLY
because there isn't an equvalent open solution which has the same reach to devices.
It’s just some configuration, what point does oauth2 have when it doesn’t work with
Facebook and Google. The whole point of our libs is to make it easy for developers to do
these complex things adding this config makes it super easy. I don’t see: ”Terrifyingly
bad karma” a good reason not to do this.