Yield doesn't mean stop
It means go unless not clear (ie stop when not clear)
If there's no oncoming traffic, then you keep going. If there is then you have to stop to allow the traffic to pass before continuing (or enter safely before said traffic reaches you).
This is fundamentally how roundabout entrances also work. You're supposed enter when you have enough time to accelerate into an open slot. You don't have to wait until it is completely clear, nor do you have to explicitly stop at an entrance.