WebRTC is a real standards-track technology. If you look at the draft you linked, none of the four editors even work for Google.
In the other cases cited - good luck making an independent interoperable implementation just from Google's "spec". The same would go for WebM and Dart.
Uh, the SPDY spec is excellent (and is IETF standards-track). The WebM "spec" might be something of a joke, but the fastest decoder right now is a third-party, independent implementation.
NaCl and Pepper are well documented (NaCl extremely so), it's just that other browser vendors (namely Mozilla) don't like Pepper's chrome-centric design and don't agree that NaCl is a good choice for the web. Dart is still being designed last I heard, but it's in a pretty similar spot; just because no one else will touch it doesn't mean there's not a decent spec for what is finished.
In the other cases cited - good luck making an independent interoperable implementation just from Google's "spec". The same would go for WebM and Dart.