We're a YC company that tries to do exactly that: WebRTC-based features that "just work", with APIs for everything you might want to do with real-time media:

  https://www.daily.co/

As you noted below, the signaling itself is the easy part. The long tail of RTCPeerConnection-related corner cases, bandwidth management, analytics and debugging real-world user experience, scaling usage both horizontally and geographically, building features like recording, scaling meeting size beyond 4 participants, optimizing for specific use cases, dealing with browser/platform quirks ... we've tried to make life easy/(ier) for developers in all of those areas.