Chrome’s WebRTC roadmap
blog.chromium.org
blog.chromium.org
1) Firefox users are used to a certain way of having their favorite browser work
2) Firefox still "promotes" version numbers, and this makes them a good target for jokes about moving so fast from version 11 to version 12, or whatever, while at this point Chrome users don't even care so much about the version anymore
I know FireFox has a more robust plugin architecture and half the time is the plugin developers' fault and FireFox has been working on a new plugin system for a while, but it's the same problems FireFox had with upgrades for years, they just happen more frequently, exacerbating the problems.
But yes, p2p multi-party chat is very possible with WebRTC. Unfortunately, there's additional overhead as each client has to send it's stream to each other client instead of having a server to multiplex it. It also means the app developer's costs are lower and of course if you want you can still PeerConnect to a server that then acts a multiplexing hub.