It's much easier to create random destructive pulses of any form of energy, than it is to use that technology in a precise, controlled manner.
A distorter, or Gravitic pulse bomb( aka jump breaker) would more than likely be fairly simple. If you compared it to the sort of precise control and long term stability needed to physically effect a reasonably sized missile.
Its the equivalent of kicking in a door rather than picking the lock..one is simple brute force..the other is finesse and control...at some point on the TL tree you get to a point where scientists and engineers can manage repulsion/tractor systems but at the average TL of Traveller they have to settle for a brick through window approach.