VoIP and video calls have lower quality and higher latency without UPnP since this often forces webRTC to tunnel through a TURN server. Networks that have neither IPv6 nor UPnP are just broken
Which is to say, you do not REQUIRE UPnP for webRTC. But yes, if you have a crap router given to you by your ISP (looking at you, SBC and Comcast) then UPnP may be your best bet. My point is you don't NEED UPnP if you have a real router.
I should be saying... thx for bringing me up to speed on this. UPnP is obviously not something I spend a lot of time on.