the faction war is not rigged simply because there is no need to do so. (think of it from the business perspective: you would need to actually pay someones workinghours to match an ingame system that runs on it own)

BUT

the player base has no invluence of the outcome of the faction war. all the players cant win against the algorythm behind the moving territories.
the faction with the bonus points will simply outmatch everything else. and it basically boils down to dumb luck wich faction had the bonus in the last turn.

if theoretically all players stoped playing and would not generate any war assets the territories would still bounce back and forth.