You can do that when simulating each bullets trajectory as well. For example straightforward setup for collision detection would be a raycast per bullet per tick and as such can work much the same way.
Indeed you can, but the idea is that a raycast is still needed. I should've been more specific in that it doesn't mean the projectile system can't do it but the idea of raycasting allows for that additional advantage cheaply and easily.
Yeah the key differentiator is a trade off between cost and simulation fidelity.