WebRTC allows peer-to-peer video conferencing through a web browser without a third party server. Which means there is no intermediary server to record the data.

Actually any peer-to-peer communication system has the property, regardless of the existence of a 'rendezvous' server to get them connected.

OK so what's wrong with WebRTC? Why do we need this other client they just invented?

WebRTC is just a protocol. You can use it any way you like. Lots of folks use it to talk to a switching server, probably because P2P IP connections can't always be made, while a server connection is guaranteed to work.