The point is "If you *have* to hit the brakes to avoid a collision in front of you". Obviously if you have a tailgating idiot behind and you can avoid the collision in front without forcing them to rear-end you, then you do that; but that's not always possible, and in that case the blame is then entirely on the person who hit you from the rear, and *not* on you for rear-ending someone.
Also even if you don’t want to get rear ended. You can at least do moderate braking and hit the debris at a slower speed. Humans make these sorts of split second tradeoffs all the time on the highway.
> Obviously if you have a tailgating idiot behind and you can avoid the collision in front without forcing them to rear-end you
That kind of consideration is where having traffic tailgating factors into it. A risk of collision (or a minor collision) may be a better option than a certain (or worse) collision with the tailgating idiot.
