If Girard had defenders of his gate beyond his own family, Familicide wouldn't have wiped out his defenses.
Also, a member of the Sapphire Guard blew up Soon's Gate, which was under siege in part because of Redcloak's grudge against the Guard's genocidal missions.
So, despite your continued insistence, bordering on pedantic, that it didn't actually happen that way, it did. And those facts I stated above are simply not true in all cases where the Gate might have been captured or destroyed.