You can't remove 11 million people from an economy and not expect that economy to contract. Anytime you remove both production and consumption from an economy it will contract. There are no two ways around that.
You really are comparing apples to oranges. You keep talking about the efficiency of a stable economy while I am talking about the size of economy. They are not the same thing and the efficiency of a stable economy is largely irrelevant to what an economy of a diminishing size will be.
No matter what 11 million people you remove from the US economy, it's going to contract. When you pick almost completely cheap laborers to remove, it's going to contract even more.
You don't believe those jobs will be taken by American workers that will keep and spend the money here instead of sending it abroad? This practise impacts our economy as well.