I have wondered that same thing from the beginning.
I was thinking they would only be used more along 'line of sight' ranges.
"Line of sight' very loosely defined here! It would still have high velocity at ranges that are occluded by the 'over the horizon' ranges.
Maybe more accurate to call it 'follows Earth's Curvature', or something.
It would be useful info to know what the projectile's velocity is at the stated 100 mile range, to enable calculations for remaing energy.
I know from long range target shooting that projectiles slow down fast.
ex:
a .308 Winchester firing a 150 grain bullet at 2750 feet per second will be travelling less than 1000 fps after only 1000 yards, and remaing energy is far less than at muzzle velocity.
With a 100 yard 'sight in', that same bullet is striking the target about 10 feet below point of aim at around that 1000 yards, and a 10 mile per hour crosswind will deflect it around 2 feet, IIRC.(fuzzy on that memory)