WebRTC, in fact, merely passes e2e encrypted packets through the TURN server (which, by the way, is only required if both sides are behind symmetric NAT: the vast majority of NAT doesn't cause this problem, though you might need to do STUN).
A lot of cell networks won't work with STUN. I've tried in personal projects to have a home computer with wifi communicate through a stun server to a mobile device using mobile data. It don't work.
> the vast majority of NAT doesn't cause this problem
A WebRTC clients behind an iptables based MASQUERADE NAT will not work without TURN. Which both incredibly common and weird that people designing WebRTC and STUN/TURN/ICE never stopped by netfilter developers to make iptables work out of box with WebRTC.
