Issue with ladders in siege is this...
When creating a balanced siege map not intended for ladder use, the mapper creates a castle or stronghold that has multiple weak points that the offense can use to get in and get to combat, otherwise it would be a meatgrinder and be boring and imbalanced (some still have this problem).
When creating a balanced siege map INTENDED for ladder use, the mapper would create a castle or stronghold that, for the most part, DOES NOT have multiple weak points - as the ladders would accomplish this.
So, the more siege equipment players have control over, the less mappers have to artificially weaken the defenses of their castles....
But this takes a whole new set of maps to work properly (or a lot of altering to existing maps), you can't use maps intended for no ladder usage and add ladders to them at free will - the result is retardedness and no chance of defense holding, just like you can't use maps intended for ladder usage without ladders, because offense would stand no chance.