"Being predictable" puts the responsibility for not getting hit on the skier who is ahead of those who are approaching them from uphill. However, it's a very good idea to be predictable, and ski a consistently narrow or wide corridor down the trail.
The skier's code of responsibility puts the responsibility to not cause a crash on the skiers who are uphill, trying to pass slower skiers ahead of them who are unpredictable. But most people don't follow this rule and ski far enough away and slow enough to avoid unpredictable skiers ahead of them. They don't even know they are in the wrong.
And we all know that being predictable is not always possible. Sometimes here in the northeast, trails get polished into ice, with little pillows of edgeable snow spaced out here and there. Skiers in over their head need to aim for those pillows and turn on them; the line will be unpredictable. There are other situations where unpredictable lines are necessary, too. It just happens.
When it does, the flummoxed skier needs to stop and wait for traffic to clear. It's also good to learn to turn your head to look back uphill without turning your shoulders, hips, and skis. This, of course, takes some time to learn to do.
The skier's code of responsibility does not cover this situation very well, which is sad.