The point you may be missing is that Deco, Jacinta and their ever growing brood is in ADDITION to Miguel, Ivanka and THEIR ever growing brood.
And as someone else mentioned in another thread, the family reunification thing has an average of 20 people being petitioned to join each individual. And in one case 70. Deco and Jacinta may have plenty of time in the sack, but they aren't going to add 20+ people to the country in the space of a couple years
Its numbers, nothing more.
Also, I'd like to point out the obvious, that there is nothing "arbitrary" about distinguishing people from different parts of the planet in relation to a specific, localised problem. You seem to have no problem doing it yourself.
Deco will continue to bleed the system and Jacinta will be happy as long as she has a house "near me Ma and me sisters"