Hey Kaiser, it's not that you'll hit something that hard. It's that you'll get your tire jambed up against something, and the sheer force of turning the wheel can cause the steering box (weakest link) to literally move on it's mounts, which can cause failure over time.

It's just like how the Nissan stock steering needs an idler arm brace; that shaft is the weakest link, originally. So you brace it, not 'cause you're hitting things hard, but because you're trying to turn the wheels when you're not moving.