Hypersonic missiles are effective because they hit their target at hypersonic speeds, where typical anti-missile counter measures (like Phalanx) have a much harder time destroying the missile. I should think the majority of anti-ship missiles never come close to going into orbit.
In fact, the more common method of attack right now is for the missile to cruise at sub-sonic speeds for the majority of the approach, and then only when within radar range of the target does the missile accelerate to hypersonic.
Further, by definition, hypersonic speed is not really possible in orbit, as hypersonic refers to the speed at which molecules start to ionize around the vehicle due to air resistance; ergo, you require atmosphere to travel at hypersonic speed...
So yes, hypersonic missiles are not magic, but they do hit their targets at hypersonic speeds, which is the whole point of designing such a missile.
Pretty ill-informed post on your part, I think.