So, if I visit a website to get, say, direct copyrighted content (let's say photo, comics, music, whatever) and that website uses webrtc to make me reshare it to other users, my legal status just went from a almost never convicted downloader to a very much punished (even though it stayed symbolic, it was still a legal loss) uploader.
Even the WebRTC standard talks quite a bit about it in the Privacy and Security Considerations section, some quotes:
Revealing IP addresses can leak location and means of connection; this can be sensitive. Depending on the network environment, it can also increase the fingerprinting surface and create persistent cross-origin state that cannot easily be cleared by the user.
[...]
These choices can for instance be made by the application based on whether the user has indicated consent to start a media connection with the other party.
https://w3c.github.io/webrtc-pc/#privacy-and-security-consid...
On standards without additional exposure, this section normally says so and is otherwise empty.
Exposing other visitors IPs is a pretty massive leak (at least some jurisdictions consider them PII, with the consequences to match), presenting that as "no additional privacy exposure" is just negligent (or more likely intentionally misleading).
Copyright: Content gets distributed by the users computer without his consent. He cannot know if he has been turned into part of a piracy network.
