because canoptek harvest exists basically.
That and stupid **** like a 60+ WC army you can do with inquistion and such, or my personal favorite of only taking the Spore Mine Formations and ending up with like 200+ models that come back on a 4+ and nothing in the army counts as a kill point.
But It'd be nice to see multiple Aspect Hosts be allowed. They are a "duplicate" detachment in name only so I could see an exception based on that possibly. That and the formation throws a bone to eldar players not spamming jetbikes and wraithknights which is awesome.