Someone can correct me if I'm wrong, but I think the difference is that "yielding" means that you should be able to come to a full and complete stop if you see

Someone can correct me if I'm wrong, but I think the difference is that "yielding" means that you should be able to come to a full and complete stop if you see oncoming traffic, whereas if you were "blowing through" at full speed, you would be unable to come to a full and complete stop in time to avoid impeding oncoming traffic. That speed changes depending on a number of factors (slope, speed, weight, distance to stop, etc).