Is spaceship armor useless?

[Mirtai]

I was speaking about GURPS Spaceships... you know, the book?

Where they list the "range" of missiles pretty specifically, pretty close to where they list the range of all the other types of weapons listed.

Missiles can technically hit targets past their range, they just automatically miss if the target can manuver, since at that point the missile is out of fuel and can't maneuver.

I'm honestly not sure what you mean by "missiles don't have a range"

Just as an example, smaller missiles (I believe they were referring to missiles in the 20 to 28 cm range) are listed as being able to reach long range, and bigger ones X (or extreme) range.

There are beam weapons that can reach the same ranges, and do so instantly, instead of taking a couple hours of flight time, for the extreme examples.

At TL 10, a SM+8 ship can hold a spinal beam weapon capable of hitting you 50,000 miles away 1/3rd of a second after they deside to do so, while a volley of missiles accelerating up to 10 mps will take more than 5000 seconds (over an hour) to travel the same distance, and will be out of fuel upon arrival. I don't care how many missiles you carry. 5000 seconds is a LONG time. Your target has tons and tons of time to deal with your missiles after killing you, if you don't have some armor to take the beam weapon hits.

I'm really not sure where the "missiles don't have ranges" idea is from. A different book?