I would interpret this to be more like sending a Bridge Module, Engineering Module, Crew Module, Cargo Module, and 2 Weapons Modules through the gate. Once there while being protected by corvettes small enough to fit whole, smaller tender craft assemble the modules into a a capital ship far too large to fit through the gates limited dimensions.
This would allow invasion forces to use the gates even if their capital ships were somewhat less efficient due to the modularity of their design. Otherwise any invasion force would be looking at long hyperspace trips or attacking space stations and battleship/carrier analogs with PT boat/cutter analogs. Sure you can send 40 of them through to attack, but none of them are going to be terribly combat effective against the much larger vessels.
-Pyrotech