Even that monster uses a spotter, because he's not a fucking idiot. Also, roaring like that evokes something primal from within you, it's contagious. Imagine a fucker like this guy charging into battle at your side in the 1400s. I'd be more afraid of him than the enemy, so I'd happily charge an enemy spear wall with this dude's terrifying roaring echoing from behind me as every man in the formation tried to match his battle cry. What a rush that would be.