Raycasts are cheap because they are just two points with an implied line between. Projectiles are great because they are a basic shape inserted into your preexi

Raycasts are cheap because they are just two points with an implied line between. Projectiles are great because they are a basic shape inserted into your preexisting physics sim that handles realistic looking gravity and collisions with everything else that has a collision shape. You could have projectiles ricochet off each other. Precomputing a trajectory loses the dynamics of collision and the cheapness of rays. Fixing projected actions into the future from one point in time can make for weird lag effects and unpredictable results for the player when a moveable piece interrupts a fixed bullet path.