This picture shows how the headset moves when you grab your front brake. See how Gap A is larger on the right than on the left? That's because the braking forces are pushing the fork towards the back of the bike. The bearing can't move because it's stuck in the cup. The only movement is at the dynamic surface between the base plate and the bearing. Notice how Gap A and Gap B are not the same in the left and right sides of this picture due to braking forces.

This picture shows how the "Integrated" headset moves when you grab your front brake. The big red arrows illustrate how the bearing not restricted from moving in the frame. This movement happens because the bearing is not fixed to the frame. Just like the conventional headset, Gap A is larger on one side than the other, but also notice Gap C. Gap C shows how the bearing is scuffing against the frame, causing wear and creaking noises.
The bearing won't be getting worn out, bearing steel is harder than anything anyone builds bike frames out of- titanium, steel, aluminum, composites- it doesn't matter, bearing steel will wear through them all. Even faster once you get a little grit and water in there. That's grinding paste.