WebRTC services are still, for the most part, isolated silos. There is no effort made to federate or interoperate between services. For that, you want something like SIP or XMPP/Jingle.
While true, my point was more that there /are/ standardized ways of doing that, and there is no barrier to apple working on and/or with standards bodies to discuss any concerns they have with WebRTC, SIP, etc.
That's not what OP was asking. WebRTC is a standard in the same way HTTP is a standard: it defines the API surface and transport for a particular set of features within the browser.
Signaling is intentionally missing from the WebRTC spec, and that is the "interesting" part here: without open and interoperable signaling, you're just preserving the status quo of proprietary video chat services such as FaceTime, Skype, Hangouts, etc. Just like HTTP enables proprietary services such as Facebook, Twitter, Google Plus, etc.
