You are right. But plagues aren’t usually associated with some sentient purpose. By their nature they are completely oblivious to anything but opportunity to multiply.
In the case of illegals, their purpose is acutely destructive and selfish. There is no one in this country that could logically and sanely argue the value added with them without inject the horse sh!t notion of dreams and wanting to do better and all that nonsense. There simply is no value added save that one liberal unicorn - an instant massive deciding vote total on their side.
It is all about “the vote”. That’s all they want. Our sovereignty and future legacy be damned. These enabling Democrats and liberals (even some citizen Hispanics) only are looking for the power, control and the money and riches that come with. They could give a damn about our founding fathers, our Constitution or our values as long as THEY gain control.
In the end, if they are allowed to succeed, the USA will become just another third-world sh!t hole with some despotic “Dreamer” in charge and disappearing his/her dissenters in the night like all the rest of South America.