The gist I get from the link is that the act of "smoothing the wave" will not benefit the one who performs the act, but it benefits the drivers behind the lane. You can't fix the traffic jam in front of you, but you can do your part to prevent one from forming behind you.
Right: like I said -- and like the GGP (jerf) just denied them saying -- the claim is that it will hasten the traffic flow. Individual vs group benefits is beside the point.
And that's why people pass around the link.