The goal is to make sure that bittorrent automatically takes full control of the interface when nobody else is using it, yet quickly gives control to whoever needs it when needed, without manual intervention from the user (the notorious "set speeds to 10% to not slow down your web browsing").
That said, uTP being based on UDP gives the nice side effect that NAT traversal is effectively possible.
uTP also implements LEDBAT, which is a scavenger class of congestion control. See CC implementation details: https://tools.ietf.org/html/rfc6817
But I though webrtc still needed dedicated servers to punch through NAT ?
http://www.html5rocks.com/en/tutorials/webrtc/infrastructure...
EDIT: confirmed: https://code.google.com/p/chromium/issues/detail?id=152875