Because they are. all the NPC's are.

let's go back to patch 2.0 ARR's early days. 1 single level 50 adventurer could run amok and cause absolute chaos in the castrums in mordhona or vineport absolutely stomp entire armies of garlean forces. yet the ENTIRE eorzean alliance could barely touch them. how incompetent must they be.

just one example. the same goes virtually everywhere in the game. NPC = not particularly competent. hahaha